作者: 网络编程  发布:2019-12-23

Overriding methods


Base type methods can be overriden by defining a Python method with the same name:

>>> class MyClass(System.ICloneable):
...    def Clone(self):
...        return MyClass()
>>> o = MyClass()
>>> o.Clone() #doctest:  ELLIPSIS
<MyClass object at ...>


IronPython does require you to provide implementations of interface methods in the class declaration. The method lookup is done dynamically when the method is accessed. Here we see that AttributeError is raised if the method is not defined:

>>> class MyClass(System.ICloneable): pass
>>> o = MyClass()
>>> o.Clone()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'MyClass' object has no attribute 'Clone'


Subclassing .NET types


Sub-classing of .NET types and interfaces is supported using class. .NET types and interfaces can be used as one of the sub-types in the class construct:

>>> class MyClass(System.Attribute, System.ICloneable, System.IComparable):
...     pass


.NET does not support multiple inheritance while Python does. IronPython allows using multiple Python classes as subtypes, and also multiple .NET interfaces, but there can only be one .NET class (other than System.Object) in the set of subtypes:

>>> class MyPythonClass1(object): pass
>>> class MyPythonClass2(object): pass
>>> class MyMixedClass(MyPythonClass1, MyPythonClass2, System.Attribute):
...     pass

和.Net相像,可以使用反射来证美赞臣(Meadjohnson卡塔尔(英语:State of Qatar)个类是或不是是有个别类的子类

Instances of the class do actually inherit from the specified .NET base type. This is important because this means that statically-typed .NET code can access the object using the .NET type. The following snippet uses Reflection to show that the object can be cast to the .NET sub-class:

>>> class MyClass(System.ICloneable):
...     pass
>>> o = MyClass()
>>> import clr
>>> clr.GetClrType(System.ICloneable).IsAssignableFrom(o.GetType())

下边又说Python并不曾真正世襲.Net子类,见类型映射表?  瞧着好玄乎

Note that the Python class does not really inherit from the .NET sub-class. See type-mapping.


>>> from System.Collections import BitArray
>>> ba = BitArray(5)
>>> ba.Set(0, "hello") # converts the second argument to True.
>>> ba[0]
>>> ba.Set(1, None) # converts the second argument to False.
>>> ba[1]

Generic methods are exposed as attributes which can be indexed with type objects. The following code calls System.Activator.CreateInstance<T>



>>> from System.Collections import BitArray
>>> ba = BitArray(5) # Creates a bit array of size 5


>>> from System.Collections import BitArray
>>> ba = BitArray(5)
>>> isinstance(type(ba), type)

Note that the Python type corresponding to a .NET type is a sub-type of type:

IronPython also supports inline initializing of the attributes of the instance. Consider the following two lines:

.NET types behave like builtin types (like list), and are immutable. i.e. you cannot add or delete descriptors from .NET types:

Methods with out parameters

Calling a method with "out" (or in-out) parameters requires explicitly passing in an instance of "clr.Reference", if you want to get the updated value from the method call. Note that COM methods with out parameters are not considered Automation-friendly [11]. JScript does not support out parameters at all. If you do run into a COM component which has out parameters, having to use "clr.Reference" is a reasonable workaround:

>>> import clr
>>> from System import Type, Activator
>>> command_type = Type.GetTypeFromProgID("ADODB.Command")
>>> command = Activator.CreateInstance(command_type)
>>> records_affected = clr.Reference[int]()
>>> command.Execute(records_affected, None, None) #doctest:  SKIP
>>> records_affected.Value

Another workaround is to leverage the inteorp assembly by using the unbound class instance method syntax of "outParamAsReturnValue = InteropAssemblyNamespace.IComInterface(comObject)".

[11] Note that the Office APIs in particular do have "VARIANT*" parameters, but these methods do not update the value of the VARIANT. The only reason they were defined with "VARIANT*" parameters was for performance since passing a pointer to a VARIANT is faster than pushing all the 4 DWORDs of the VARIANT onto the stack. So you can just treat such parameters as "in" parameters.

Accessing the type library

The type library has names of constants. You can use clr.AddReferenceToTypeLibrary to load the type library.

在ironPython 中想使用.Net的API必需初始入 CLCRUISER,借用CL奇骏导入.Net的类,最常用的是上边这种导法

__repr__/__str__ on .NET objects


All Python user types have __repr__ and __str__:

>>> class MyClass(object):
...     pass
>>> o = MyClass()
>>> o.__repr__() #doctest:  ELLIPSIS
'<MyClass object at ...>'
>>> o.__str__() #doctest:  ELLIPSIS
>>> str(o) #doctest:  ELLIPSIS
'<MyClass object at ...>'

For .NET types which do not override ToString, IronPython provides __repr__ and __str__ methods which behave similar to those of Python user types [10]:

想见:不重写.Net对象的 ToString方法的目的,它让你能够把它当成Python对象来管理,即便您想改写Tostring就重写它的__repr__和_-str__主意就好了?

>>> from System.Collections import BitArray
>>> ba = BitArray(5)
>>> ba.ToString() # BitArray inherts System.Object.ToString()
>>> ba.__repr__() #doctest:  ELLIPSIS
'<System.Collections.BitArray object at ... [System.Collections.BitArray]>'
>>> ba.__str__() #doctest:  ELLIPSIS
'<System.Collections.BitArray object at ... [System.Collections.BitArray]>'

For .NET types which do override ToString, IronPython includes the result of ToString in __repr__, and maps ToString directly to __str__:

估算:若是ToString得不到您想要的结果,那么结果也许包罗在__repr__和__str__ 方法里头?

>>> e = System.Exception()
>>> e.ToString()
"System.Exception: Exception of type 'System.Exception' was thrown."
>>> e.__repr__() #doctest:  ELLIPSIS
"<System.Exception object at ... [System.Exception: Exception of type 'System.Exception' was thrown.]>"
>>> e.__str__() #doctest:
"System.Exception: Exception of type 'System.Exception' was thrown."

For Python types that override ToString, __str__ is mapped to the ToString override:


>>> class MyClass(object):
...     def ToString(self):
...         return "ToString implemented in Python"
>>> o = MyClass()
>>> o.__repr__() #doctest:  ELLIPSIS
'<MyClass object at ...>'
>>> o.__str__()
'ToString implemented in Python'
>>> str(o) #doctest:  ELLIPSIS
'<MyClass object at ...>'

There is some inconsistency in handling of __str__ that is tracked by

上边这段大致是说在IronPython里不曾像多数高端语言中有 ref和out的定义,在IronPython中对此这种输出援用有二种耍法,后生可畏种隐式的风流浪漫种显式的

>>> ba = BitArray(5, Length = 10)

Invoking .NET instance methods works just like invoking methods on a Python object using the attribute notation:


>>> System.Object.ReferenceEquals is System.GC.ReferenceEquals
>>> ba.Set(index = 1, value = True)
>>> ba[1]

Accessing protected members of base types

想来:上面这段文书档案写的很冲突,第生机勃勃段给了生机勃勃段代码说IronPython中大器晚成经不在子类中向来调用Protected类型的情势会不让访谈,但第二段内容中又建议说实在在python中并从未private protected等等那个概念的存在,並且方法是可以动态增进和删除的,



Normally, IronPython does not allow access to protected members (unless you are using private-binding). For example, accessing MemberwiseClone causes a TypeError since it is a protected method:

>>> import clr
>>> import System
>>> o = System.Object()
>>> o.MemberwiseClone()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: cannot access protected member MemberwiseClone without a python subclass of object

IronPython does allow Python sub-types to access protected members of .NET base types. However, Python does not enforce any accessibility rules. Also, methods can be added and removed dynamically from a class. Hence, IronPython does not attempt to guard access to protected members of .NET sub-types. Instead, it always makes the protected members available just like public members:

>>> class MyClass(System.Object):
...     pass
>>> o = MyClass()
>>> o.MemberwiseClone() #doctest:  ELLIPSIS
<MyClass object at ...>

The Python language passes all arguments by-value. There is no syntax to indicate that an argument should be passed by-reference like there is in .NET languages like C# and VB.NET via the ref and out keywords. IronPython supports two ways of passing ref or out arguments to a method, an implicit way and an explicit way.



OleAutomation and COM interop


IronPython supports accessing OleAutomation objects (COM objects which support dispinterfaces).

IronPython does not support the win32ole library, but Python code using win32ole can run on IronPython with just a few modifications.

Calling from Python


When you call a method from Python, and the method overrides a .NET method from a base type, the call is performed as a regular Python call. The arguments do not undergo conversion, and neither are they modified in any way like being wrapped with clr.Reference. Thus, the call may need to be written differently than if the method was overriden by another language. For example, trying to call TryGetValue on the MyDictionary type from the overriding-ref-args section as shown below results in a TypeError, whereas a similar call works with System.Collections.Generic.Dictionary[str, float]:

>>> result, value = d.TryGetValue("yes")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: TryGetValue() takes exactly 3 arguments (2 given)
>>> from System.Guid import *
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: no module named Guid
>>> s = "hello"
>>> System.Object.GetHashCode(s) == System.String.GetHashCode(s)
>>> from System.Runtime.CompilerServices import RuntimeHelpers
>>> RuntimeHelpers.GetHashCode(s) == System.String.GetHashCode(s)

Nested types are also imported:

Note that there might exist a non-generic type as well as one or more generic types with the same name [1]. In this case, the name can be used without any indexing to access the non-generic type, and it can be indexed with different number of types to access the generic type with the corresponding number of type parameters. The code below accesses System.EventHandler and also System.EventHandler<TEventArgs>



>>> del list.append
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: cannot delete attribute 'append' of builtin type 'list'
>>> import System
>>> del System.DateTime.ToByteArray
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can't set attributes of built-in/extension type 'DateTime'

Overiding events


Events have underlying methods which can be obtained using EventInfo.GetAddMethod and EventInfo.GetRemoveMethod

>>> from System.ComponentModel import IComponent
>>> import clr
>>> event_info = clr.GetClrType(IComponent).GetEvent("Disposed")
>>> event_info.GetAddMethod().Name
>>> event_info.GetRemoveMethod().Name

To override events, you need to define methods with the name of the underlying methods:

>>> class MyComponent(IComponent):
...     def __init__(self):
...         self.dispose_handlers = []
...     def Dispose(self):
...         for handler in self.dispose_handlers:
...             handler(self, EventArgs())
...     def add_Disposed(self, value):
...         self.dispose_handlers.append(value)
...     def remove_Disposed(self, value):
...         self.dispose_handlers.remove(value)
...     # Other methods of IComponent not implemented for brevity
>>> c = MyComponent()
>>> def callback(sender, event_args):
...     print event_args
>>> args = System.Array[object]((System.EventHandler(callback),))
>>> # Use Reflection to simulate a call from another .NET language
>>> event_info.GetAddMethod().Invoke(c, args)
>>> c.Dispose() #doctest:  ELLIPSIS
<System.EventArgs object at ... [System.EventArgs]>

When the argument type does not exactly match the parameter type expected by the .NET method, IronPython tries to convert the argument. IronPython uses conventional .NET conversion rules like conversion operators , as well as IronPython-specific rules. This snippet shows how arguments are converted when calling theSet(System.Int32, System.Boolean) method:


This allows a unified (Pythonic) view of both Python and .NET types. For example, isinstance works with .NET types as well:

估量:所以object的GetHashCode和String的GetHashCode是如出意气风发辙的,因为string 世袭于object,然则string的GetHashCode方法和RunTimeHelpers类中的GetHashCode差别,估摸,只怕是因为实际完成分裂,解释器能够透过IL代码分辨出达成是不是相通?

If need to get the System.Type instance for the .NET type, you need to use clr.GetClrType. Conversely, you can use clr.GetPythonType to get a type object corresponding to a System.Type object.


ToString on Python objects

假诺对叁个Python对象使用 ToString,尽管信守Python的玩的方法,你重写了__str__主意,你调用ToString解释器还是会去调用.Net里的至极toString方法,并不会调用你定义的那个__str__办法,猜测:约等于说只要一个类是一而再连续自.Net的,那她的规规矩矩正是依据


Calling ToString on Python objects calls the default System.Object.ToString implementation, even if the Python type defines __str__:

>>> class MyClass(object):
...     def __str__(self):
...         return "__str__ result"
>>> o = MyClass()
>>> # Use Reflection to simulate a call from another .NET language
>>> o.GetType().GetMethod("ToString").Invoke(o, None) #doctest:  ELLIPSIS

All .NET assemblies have a unique version number which allows using a specific version of a given assembly. The following code will load the version of System.Xml.dll that ships with .NET 2.0 and .NET 3.5:


Using the DLR Hosting APIs

想来:大致是说.net能够动用DL兰德酷路泽 Hosting Api来实行ironPython代码

The DLR Hosting APIs allow a .NET application to embed DLR languages like IronPython and IronRuby, load and execute Python and Ruby code, and access objects created by the Python or Ruby code.


>>> from System import Environment
>>> Environment
<type 'Environment'>

>>> from System import *
>>> Environment
<type 'Environment'>


>>> from System.Collections.Generic import List, Dictionary
>>> int_list = List[int]()
>>> str_float_dict = Dictionary[str, float]()

以下笔记仅记录阅读进度中自己觉着有至关重要记录的源委,大比非常多都以依据翻译软件的机翻,合营个人对代码的敞亮写出的笔记,个别不是很明确的,会在句首标记  估算:

>>> Enumerable.Any(list, lambda x : x < 2)


Relationship of classes in Python code and normal .NET types


A class definition in Python does not map directly to a unique .NET type. This is because the semantics of classes is different between Python and .NET. For example, in Python it is possible to change the base types just by assigning to the __bases__ attribute on the type object. However, the same is not possible with .NET types. Hence, IronPython implements Python classes without mapping them directly to .NET types. IronPython does use some .NET type for the objects, but its members do not match the Python attributes at all. Instead, the Python class is stored in a .NET field called .class, and Python instance attributes are stored in a dictionary that is stored in a .NET field called .dict [7]

>>> import clr
>>> class MyClass(object):
...     pass
>>> o = MyClass()
>>> o.GetType().FullName #doctest:  ELLIPSIS
>>> [field.Name for field in o.GetType().GetFields()]
['.class', '.dict', '.slots_and_weakref']
>>> o.GetType().GetField(".class").GetValue(o) == MyClass
>>> class MyClass2(MyClass):
...    pass
>>> o2 = MyClass2()
>>> o.GetType() == o2.GetType()

Also see Type-system unification (type and System.Type)

[7] These field names are implementation details, and could change.

Extension methods

当下IronPython对于增添方法的帮助还不好,无法像C#那么间接调用,只可以通过静态方法来调用,譬喻,要是string有多少个substring方法是后来扩展的,在c#您能够写成"sadsad".substring(...卡塔尔(قطر‎,然而在IronPython你只好写成System.String.SubString("sadsad"卡塔尔(英语:State of Qatar)

Extension methods are currently not natively supported by IronPython. Hence, they cannot be invoked like instance methods. Instead, they have to be invoked like static methods.



.NET indexers are exposed as __getitem__ and __setitem__. Thus, the Python indexing syntax can be used to index .NET collections (and any type with an indexer):

>>> from System.Collections import BitArray
>>> ba = BitArray(5)
>>> ba[0]
>>> ba[0] = True
>>> ba[0]


The indexer can be called using the unbound class instance method syntax using __getitem__ and __setitem__. This is useful if the indexer is virtual and is implemented as an explicitly-implemented interface method:

>>> BitArray.__getitem__(ba, 0)


>>> from System.Environment import *
>>> Exit is System.Environment.Exit

.NET allows a method with a different name to override a base method implementation or interface method slot. This is useful if a type implements two interfaces with methods with the same name. This is known as explicity implemented interface methods. For example, Microsoft.Win32.RegistryKey implementsSystem.IDisposable.Dispose explicitly:

>>> import clr
>>> clr.AddReference("System.Xml")

See appendix-type-conversion-rules for the detailed conversion rules. Note that some Python types are implemented as .NET types and no conversion is required in such cases. See builtin-type-mapping for the mapping.

>>> OSVersion
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'OSVersion' is not defined
>>> System.Environment.OSVersion #doctest:  ELLIPSIS
<System.OperatingSystem object at ...>

>>> ba = BitArray(5.0)
>>> ba = BitArray(5)
>>> ba.Length = 10

Overriding properties

上面这段大致是说.net里属性都会有意气风发对get set方法,那么些主意是被含有在质量原数据定义里的,假若用python重写.net类的习性,只须要重写get_属性名 就能够兑现对属性重临值的校正,推测:而set方法就如是只读的,不让重写?

.NET properties are backed by a pair of .NET methods for reading and writing the property. The C# compiler automatically names them as get_<PropertyName> and set_<PropertyName>. However, .NET itself does not require any specific naming pattern for these methods, and the names are stored in the the metadata associated with the property definition. The names can be accessed using the GetGetMethod and GetSetMethods of the System.Reflection.PropertyInfo class:

>>> import clr
>>> import System
>>> StringCollection = System.Collections.Generic.ICollection[str]
>>> prop_info = clr.GetClrType(StringCollection).GetProperty("Count")
>>> prop_info.GetGetMethod().Name
>>> prop_info.GetSetMethod() # None because this is a read-only property

Overriding a virtual property requires defining a Python method with the same names as the underlying getter or setter .NET method:

>>> class MyCollection(StringCollection):
...    def get_Count(self):
...        return 100
...    # Other methods of ICollection not overriden for brevity
>>> c = MyCollection()
>>> # Use Reflection to simulate a call from another .NET language
>>> prop_info.GetGetMethod().Invoke(c, None)

If you want to control the exact overload that gets called, you can use the Overloads method on method objects:



It is sometimes required to have control over the .NET type generated for the Python class. This is because some .NET APIs expect the user to define a .NET type with certain attributes and members. For example, to define a pinvoke method, the user is required to define a .NET type with a .NET method marked withDllImportAttribute , and where the signature of the .NET method exactly describes the target platform method.

Starting with IronPython 2.6, IronPython supports a low-level hook which allows customization of the .NET type corresponding to a Python class. If the metaclass of a Python class has an attribute called __clrtype__, the attribute is called to generate a .NET type. This allows the user to control the the details of the generated .NET type. However, this is a low-level hook, and the user is expected to build on top of it.

The ClrType sample available in the IronPython website shows how to build on top of the __clrtype__ hook.


>>> from System.Collections.Generic import IEnumerable, List
>>> list = List[int]([1, 2, 3])
>>> import clr
>>> clr.AddReference("System.Core")
>>> from System.Linq import Enumerable
>>> Enumerable.Any[int](list, lambda x : x < 2)
>> ba = BitArray.__new__(BitArray, 5)

>>> type(BitArray.Xor)
<type 'method_descriptor'>
>>> type(ba.Xor)
<type 'builtin_function_or_method'>


>>> rkey = Registry.CurrentUser.OpenSubKey("Software")
>>> System.IDisposable.Dispose(rkey)
>>> from Microsoft.Win32 import RegistryKey
>>> clr.GetClrType(RegistryKey).GetMethod("Flush") #doctest:  ELLIPSIS
<System.Reflection.RuntimeMethodInfo object at ... [Void Flush()]>
>>> clr.GetClrType(RegistryKey).GetMethod("Dispose")
>>> import System
>>> System.Environment
<type 'Environment'>



Python functions and bound instance methods can be converted to delegates:

>>> from System import EventHandler, EventArgs
>>> def foo(sender, event_args):
...     print event_args
>>> d = EventHandler(foo)
>>> d(None, EventArgs()) #doctest:  ELLIPSIS
<System.EventArgs object at ... [System.EventArgs]>

Some of the conversions supported are:

>>> isinstance(type(ba), type)
>>> type(ba) is type



IronPython also allows the signature of the Python function or method to be different (though compatible) with the delegate signature. For example, the Python function can use keyword arguments:

>>> def foo(*args):
...     print args
>>> d = EventHandler(foo)
>>> d(None, EventArgs()) #doctest:  ELLIPSIS
(None, <System.EventArgs object at ... [System.EventArgs]>)


If the return type of the delegate is void, IronPython also allows the Python function to return any type of return value, and just ignores the return value:

>>> def foo(*args):
...     return 100 # this return value will get ignored
>>> d = EventHandler(foo)
>>> d(None, EventArgs())


If the return value is different, IronPython will try to convert it:

>>> def foo(str1, str2):
...     return 100.1 # this return value will get converted to an int
>>> d = System.Comparison[str](foo)
>>> d("hello", "there")

TODO - Delegates with out/ref parameters


.NET types are exposed as Python classes. Like Python classes, you usually cannot import all the attributes of .NET types using from <name> import *:

>>> from System import Activator, Guid
>>> guid = Activator.CreateInstance[Guid]()


Enumerable.Any[int](list, lambda x : x < 2)

Enumerable.Any(list, lambda x : x < 2)

Non-default .NET indexers


Note that a default indexer is just a property (typically called Item) with one argument. It is considered as an indexer if the declaraing type uses DefaultMemberAttribute to declare the property as the default member.

See property-with-parameters for information on non-default indexers.



.NET properties are exposed similar to Python attributes. Under the hood, .NET properties are implemented as a pair of methods to get and set the property, and IronPython calls the appropriate method depending on whether you are reading or writing to the properity:

>>> from System.Collections import BitArray
>>> ba = BitArray(5)
>>> ba.Length # calls "BitArray.get_Length()"
>>> ba.Length = 10 # calls "BitArray.set_Length()"


To call the get or set method using the unbound class instance method syntax, IronPython exposes methods called GetValue and SetValue on the property descriptor. The code above is equivalent to the following:

>>> ba = BitArray(5)
>>> BitArray.Length.GetValue(ba)
>>> BitArray.Length.SetValue(ba, 10)

上边这段大致是说在IronPython里索引.Net类型中的群集数组的措施以至走访属性的艺术,直接待上访谈属性,调用get/set, 调用 对象.Item[?]的方法访谈对象

.NET properties are exposed similar to Python attributes. Under the hood, .NET properties are implemented as a pair of methods to get and set the property, and IronPython calls the appropriate method depending on whether you are reading or writing to the properity:

>>> from System.Collections import BitArray
>>> ba = BitArray(5)
>>> ba.Length # calls "BitArray.get_Length()"
>>> ba.Length = 10 # calls "BitArray.set_Length()"

To call the get or set method using the unbound class instance method syntax, IronPython exposes methods called GetValue and SetValue on the property descriptor. The code above is equivalent to the following:

>>> ba = BitArray(5)
>>> BitArray.Length.GetValue(ba)
>>> BitArray.Length.SetValue(ba, 10)

Methods with multiple overloads


*args在Python 语法中象征兵接兵收率性个不限类型的参数

Python does not support method overloading. A class can have only one method with a given name. As a result, you cannot override specific method overloads of a .NET sub-type. Instead, you need to use define the function accepting an arbitrary argument list (see _tut-arbitraryargs), and then determine the method overload that was invoked by inspecting the types of the arguments:

>>> import clr
>>> import System
>>> StringComparer = System.Collections.Generic.IEqualityComparer[str]
>>> class MyComparer(StringComparer):
...     def GetHashCode(self, *args):
...          if len(args) == 0:
...              # Object.GetHashCode() called
...              return 100
...          if len(args) == 1 and type(args[0]) == str:
...              # StringComparer.GetHashCode() called
...              return 200
...          assert("Should never get here")
>>> comparer = MyComparer()
>>> getHashCode1 = clr.GetClrType(System.Object).GetMethod("GetHashCode")
>>> args = System.Array[object](["another string"])
>>> getHashCode2 = clr.GetClrType(StringComparer).GetMethod("GetHashCode")
>>> # Use Reflection to simulate a call to the different overloads
>>> # from another .NET language
>>> getHashCode1.Invoke(comparer, None)
>>> getHashCode2.Invoke(comparer, args)


Determining the exact overload that was invoked may not be possible, for example, if None is passed in as an argument.


Accessing Python code from other .NET code


Statically-typed languages like C# and VB.Net can be compiled into an assembly that can then be used by other .NET code. However, IronPython code is executed dynamically using ipy.exe. If you want to run Python code from other .NET code, there are a number of ways of doing it.


Invoking static .NET methods is similar to invoking Python static methods:

You can also call the __new__ method to create an instance:

IronPython also supports dict arguments:

Some .NET types only have static methods, and are comparable to namespaces. C# refers to them as static classes , and requires such classes to have only static methods. IronPython allows you to import all the static methods of such static classes. System.Environment is an example of a static class:


Generic methods


泛型方法,那几个文书档案通篇大量选拔clr的反射方法来调用.net,作者不知晓是还是不是必需这么做技巧调用,如若是的话,那可真是太难为了, 并且品质相对不咋地

When you override a generic method, the type parameters get passed in as arguments. Consider the following generic method declaration:

// csc /t:library /out:convert.dll convert.cs
public interface IMyConvertible {
    T1 Convert<T1, T2>(T2 arg);

The following code overrides the generic method Convert:

>>> import clr
>>> clr.AddReference("convert.dll")
>>> import System
>>> import IMyConvertible
>>> class MyConvertible(IMyConvertible):
...     def Convert(self, t2, T1, T2):
...         return T1(t2)
>>> o = MyConvertible()
>>> # Use Reflection to simulate a call from another .NET language
>>> type_params = System.Array[System.Type]([str, float])
>>> convert = clr.GetClrType(IMyConvertible).GetMethod("Convert")
>>> convert_of_str_float = convert.MakeGenericMethod(type_params)
>>> args = System.Array[object]([100.1])
>>> convert_of_str_float.Invoke(o, args)


Generic method receive information about the method signature being invoked, whereas normal method overloads do not. The reason is that .NET does not allow normal method overloads to differ by the return type, and it is usually possible to determine the argument types based on the argument values. However, with generic methods, one of the type parameters may only be used as the return type. In that case, there is no way to determine the type paramter.



It is sometimes desirable to invoke an instance method using the unbound class instance method and passing an explicit self object as the first argument. For example, .NET allows a class to declare an instance method with the same name as a method in a base type, but without overriding the base method. SeeSystem.Reflection.MethodAttributes.NewSlot for more information. In such cases, using the unbound class instance method syntax allows you chose precisely which slot you wish to call:

Value types


Python expects all mutable values to be represented as a reference type. .NET, on the other hand, introduces the concept of value types which are mostly copied instead of referenced. In particular .NET methods and properties returning a value type will always return a copy.

This can be confusing from a Python programmer’s perspective since a subsequent update to a field of such a value type will occur on the local copy, not within whatever enclosing object originally provided the value type.

While most .NET value types are designed to be immutable, and the .NET design guidelines recommend value tyeps be immutable, this is not enforced by .NET, and so there do exist some .NET valuetype that are mutable. TODO - Example.

For example, take the following C# definitions:

struct Point {
    # Poorly defined struct - structs should be immutable
    public int x;
    public int y;

class Line {
    public Point start;
    public Point end;

    public Point Start { get { return start; } }
    public Point End { get { return end; } }

If line is an instance of the reference type Line, then a Python programmer may well expect "line.Start.x = 1" to set the x coordinate of the start of that line. In fact the property Start returned a copy of the Point value type and it’s to that copy the update is made:

print line.Start.x    # prints ‘0’
line.Start.x = 1
print line.Start.x    # still prints ‘0’

This behavior is subtle and confusing enough that C# produces a compile-time error if similar code is written (an attempt to modify a field of a value type just returned from a property invocation).

Even worse, when an attempt is made to modify the value type directly via the start field exposed by Line (i.e. “`line.start.x = 1`”), IronPython will still update a local copy of the Point structure. That’s because Python is structured so that “” will always produce a useable value: in the case above “line.start” needs to return a full value type which in turn implies a copy.

C#, on the other hand, interprets the entirety of the “`line.start.x = 1`” statement and actually yields a value type reference for the “line.start” part which in turn can be used to set the “x” field in place.

This highlights a difference in semantics between the two languages. In Python “line.start.x = 1” and “foo = line.start; foo.x = 1” are semantically equivalent. In C# that is not necessarily so.

So in summary: a Python programmer making updates to a value type embedded in an object will silently have those updates lost where the same syntax would yield the expected semantics in C#. An update to a value type returned from a .NET property will also appear to succeed will updating a local copy and will not cause an error as it does in the C# world. These two issues could easily become the source of subtle, hard to trace bugs within a large application.

In an effort to prevent the unintended update of local value type copies and at the same time preserve as pythonic and consistent a view of the world as possible, direct updates to value type fields are not allowed by IronPython, and raise a ValueError:

>>> line.start.x = 1 #doctest:  SKIP
Traceback (most recent call last):
   File , line 0, in input##7
ValueError Attempt to update field x on value type Point; value type fields can not be directly modified

This renders value types “mostly” immutable; updates are still possible via instance methods on the value type itself.


However, it is possible that the type has another method with the same name. In that case, the explicitly implemented method is not accessible as an attribute. However, it can still be called by using the unbound class instance method syntax:


>>> import clr
>>> r = clr.Reference[float]()
>>> d.TryGetValue("b", r)
>>> r.Value
>>> import clr
>>> clr.AddReference("System.Xml, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089")

在CLR引入.Net大类之后,就可以使用Python代码正式导入这些类,在IronPython中,会将这些.Net 转化为Python类来对待,但如果使用类示例对比,会发现无论你对比的是.Net类还是Python类,都成立。
可以使用import 直接导入命名空间下所有东西,也可以用from x import x【,x...】的语法选择性的导入个别需要被用到的类

>>> import System
>>> System #doctest:  ELLIPSIS
<module 'System' (CLS module, ... assemblies loaded)>
>>> System.Collections #doctest:  ELLIPSIS
<module 'Collections' (CLS module, ... assemblies loaded)>

Compiling Python code into an assembly


The pyc sample can be used to compile IronPython code into an assembly. The sample builds on top of clr-CompileModules. The assembly can then be loaded and executed using Python-ImportModule. However, note that the MSIL in the assembly is not CLS-compliant and cannot be directly accessed from other .NET languages.

The types in the namespaces are exposed as Python types, and are accessed as attributes of the namespace. The following code accesses the System.Environment class from mscorlib.dll:


System.Object.ToString, __repr__ and __str__

>>> d = { "a":100.1, "b":200.2, "c":300.3 }
>>> from System.Collections.Generic import Dictionary
>>> d = Dictionary[str, float](d)
>>> d.TryGetValue("b")
(True, 200.2)
>>> d.TryGetValue("z")
(False, 0.0)

Proxy types


IronPython cannot directly use System.MarshalByRefObject instances. IronPython uses reflection at runtime to determine how to access an object. However, System.MarshalByRefObject instances do not support reflection.

You can use unbound-class-instance-method syntax to call methods on such proxy objects.



There is one important detail worth pointing out. IronPython tries to use the type library of the OleAut object if it can be found, in order to do name resolution while accessing methods or properties. The reason for this is that the IDispatch interface does not make much of a distinction between properties and method calls. This is because of Visual Basic 6 semantics where "excel.Quit" and "excel.Quit()" have the exact same semantics. However, IronPython has a strong distinction between properties and methods, and methods are first class objects. For IronPython to know whether "excel.Quit" should invoke the method Quit, or just return a callable object, it needs to inspect the typelib. If a typelib is not available, IronPython assumes that it is a method. So if a OleAut object has a property called "prop" but it has no typelib, you would need to write "p = obj.prop()" in IronPython to read the property value.

.NET Exceptions


raise can raise both Python exceptions as well as .NET exceptions:

>>> raise ZeroDivisionError()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
>>> import System
>>> raise System.DivideByZeroException()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ZeroDivisionError: Attempted to divide by zero.


The except keyword can catch both Python exceptions as well as .NET exceptions:

>>> try:
...    import System
...    raise System.DivideByZeroException()
... except System.DivideByZeroException:
...    print "This line will get printed..."
This line will get printed...



IronPython implements the Python exception mechanism on top of the .NET exception mechanism. This allows Python exception thrown from Python code to be caught by non-Python code, and vice versa. However, Python exception objects need to behave like Python user objects, not builtin types. For example, Python code can set arbitrary attributes on Python exception objects, but not on .NET exception objects:

>>> e = ZeroDivisionError()
>>> = 1 # this works
>>> e = System.DivideByZeroException()
>>> = 1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'DivideByZeroException' object has no attribute 'foo'


To support these two different views, IronPython creates a pair of objects, a Python exception object and a .NET exception object, where the Python type and the .NET exception type have a unique one-to-one mapping as defined in the table below. Both objects know about each other. The .NET exception object is the one that actually gets thrown by the IronPython runtime when Python code executes a raise statement. When Python code uses the except keyword to catch the Python exception, the Python exception object is used. However, if the exception is caught by C# (for example) code that called the Python code, then the C# code naturally catches the .NET exception object.

The .NET exception object corresponding to a Python exception object can be accessed by using the clsException attribute (if the module has excecuted import clr):

>>> import clr
>>> try:
...     1/0
... except ZeroDivisionError as e:
...     pass
>>> type(e)
<type 'exceptions.ZeroDivisionError'>
>>> type(e.clsException)
<type 'DivideByZeroException'>


IronPython is also able to access the Python exception object corresponding to a .NET exception object [5], thought this is not exposed to the user [6].


The Python exception object corresponding to a .NET exception object is accessible (to the IronPython runtime) via the System.Exception.Data property. Note that this is an implementation detail and subject to change:

>>> e.clsException.Data["PythonExceptionInfo"] #doctest:  ELLIPSIS
<IronPython.Runtime.Exceptions.PythonExceptions ExceptionDataWrapper object at ...>


[6] ... except via the DLR Hosting API ScriptEngine.GetService<ExceptionOperations>().GetExceptionMessage

Python exception

.NET exception











System.InvalidOperationException subtype











































IP.O.SyntaxErrorException (System.Data has something close)




















































































Given that raise results in the creation of both a Python exception object and a .NET exception object, and given that rescue can catch both Python exceptions and .NET exceptions, a question arises of which of the exception objects will be used by the rescue keyword. The answer is that it is the type used in the rescue clause. i.e. if the rescue clause uses the Python exception, then the Python exception object will be used. If the rescue clause uses the .NET exception, then the .NET exception object will be used.

The following example shows how 1/0 results in the creation of two objects, and how they are linked to each other. The exception is first caught as a .NET exception. The .NET exception is raised again, but is then caught as a Python exception:

>>> import System
>>> try:
...     try:
...         1/0
...     except System.DivideByZeroException as e1:
...         raise e1
... except ZeroDivisionError as e2:
...     pass
>>> type(e1)
<type 'DivideByZeroException'>
>>> type(e2)
<type 'exceptions.ZeroDivisionError'>
>>> e2.clsException is e1

上边这段说的是假若Python顾客定义了叁个Python类世襲.Net的Exception对象,然后代码中抓获到了那几个极度,然后用.Net非常新闻的读取情势去会见拾贰分信息,你将什么也看不到,在下文中极其音信应该是"some message",不过用.net的格局访问,你只会见到

'Python Exception: MyException'

Python user-defined exceptions get mapped to System.Exception. If non-Python code catches a Python user-defined exception, it will be an instance of System.Exception, and will not be able to access the exception details:

>>> # since "Exception" might be System.Exception after "from System import *"
>>> if "Exception" in globals(): del Exception
>>> class MyException(Exception):
...     def __init__(self, value):
...         self.value = value
...     def __str__(self):
...         return repr(self.value)
>>> try:
...     raise MyException("some message")
... except System.Exception as e:
...     pass
>>> clr.GetClrType(type(e)).FullName
>>> e.Message
'Python Exception: MyException'


In this case, the non-Python code can use the ScriptEngine.GetService<ExceptionOperations>().GetExceptionMessage DLR Hosting API to get the exception message.


TODO What happens if the sub-type has a static method with the same name but a different signature? Are both overloads available or not?

>>> from System.Guid import NewGuid, ToByteArray
>>> g = NewGuid()
>>> ToByteArray(g) #doctest:  ELLIPSIS

Like Python static methods, the .NET static method can be accessed as an attribute of sub-types as well:

>>> int_bool_new = BitArray.__new__.Overloads[int, type(True)]
>>> ba = int_bool_new(BitArray, 5, True) # calls __new__(System.Int32, System.Boolean)
>>> ba = int_bool_new(BitArray, 5, "hello") # converts "hello" to a System.Boolan
>>> ba = int_bool_new(BitArray, 5)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: __new__() takes exactly 2 arguments (1 given)

Equality and hashing

TODO - This is currently just copied from IronRuby, and is known to be incorrect

Object equality and hashing are fundamental properties of objects. The Python API for comparing and hashing objects is __eq__ (and __ne__) and __hash__ respectively. The CLR APIs are System.Object.Equals and System.Object.GetHashCode respectively. IronPython does an automatic mapping between the two concepts so that Python objects can be compared and hashed from non-Python .NET code, and __eq__ and __hash__ are available in Python code for non-Python objects as well.

When Python code calls __eq__ and __hash__

  • If the object is a Python object, the default implementations of __eq__ and __hash__ get called. The default implementations call System.Object.ReferenceEquals and System.Runtime.CompileServices.RuntimeHelpers.GetHashCode respectively.
  • If the object is a CLR object, System.Object.Equals and System.Object.GetHashCode respectively get called on the .NET object.
  • If the object is a Python subclass object inheriting from a CLR class, the CLR's class's implementation of System.Object.Equals and System.Object.GetHashCode will get called if the Python subclass does not define __eq__ and __hash__. If the Python subclass defines __eq__ and __hash__, those will be called instead.

When static MSIL code calls System.Object.Equals and System.Object.GetHashCode

  • If the object is a Python objects, the Python object will direct the call to __eq__ and __hash__. If the Python object has implementations for these methods, they will be called. Otherwise, the default implementation mentioned above gets called.
  • If the object is a Python subclass object inheriting from a CLR class, the CLR's class's implementation of System.Object.Equals and System.Object.GetHashCode will get called if the Python subclass does not define __eq__ and __hash__. If the Python subclass defines __eq__ and __hash__, those will be called instead.

In many cases, the type parameter can be inferred based on the arguments passed to the method call. Consider the following use of a generic method [3]:

With generic type parameter inference, the last statement can also be written as:

IronPython also supports named arguments:

>>> from System.Collections import BitArray
>>> ba = BitArray(5)
>>> ba.Set(0, True) # call the Set method
>>> ba[0]

In such cases, IronPython tries to expose the method using its simple name - if there is no ambiguity:

The above two lines are equivalent to this single line:

>>> from System import EventHandler, EventArgs
>>> EventHandler # this is the combo type object
<types 'EventHandler', 'EventHandler[TEventArgs]'>
>>> # Access the non-generic type
>>> dir(EventHandler) #doctest:  ELLIPSIS
['BeginInvoke', 'Clone', 'DynamicInvoke', 'EndInvoke', ...
>>> # Access the generic type with 1 type paramter
>>> dir(EventHandler[EventArgs]) #doctest:  ELLIPSIS
['BeginInvoke', 'Call', 'Clone', 'Combine', ...

很多时候在IronPython 中并不支持一口气导入整个命名空间里所有东西

.NET types are exposed as Python classes, and you can do many of the same operations on .NET types as with Python classes. In either cases, you create an instance by calling the type:


.NET represents types using System.Type. However, when you access a .NET type in Python code, you get a Python type object [2]:

However, note that IronPython will raise a TypeError if there are conversions to more than one of the overloads:

You can import specific members, both static and instance:

Integration of Python and .NET features

下边这段差非常少是介绍 Python和.Net特征统生龙活虎化在IronPython中的一些反映,举个例子支持python的doc成效读.Net的API文书档案,又大概读不到就一向通过反射来读取一些有关那些类的消息

  • Type system integration.

    • See "Type-system unification (type and System.Type)"
    • Also see extensions-to-python-types and extensions-to-dotnet-types
  • List comprehension works with any .NET type that implements IList

  • with works with with any System.Collections.IEnumerable or System.Collections.Generic.IEnumerable<T>

  • pickle and ISerializable

  • __doc__ on .NET types and members:

    • __doc__ uses XML comments if available. XML comment files are installed if TODO. As a result, help can be used:

      >>> help(System.Collections.BitArray.Set) #doctest:  NORMALIZE_WHITESPACE
      Help on method_descriptor:
          Set(self, int index, bool value)
                          Sets the bit at a specific
           position in the System.Collections.BitArray to
           the specified value.
                          The zero-based index of the
           bit to set.
                          The Boolean value to assign
           to the bit.
    • If XML comment files are not available, IronPython generates documentation by reflecting on the type or member:

      >>> help(System.Collections.Generic.List.Enumerator.Current) #doctest:  NORMALIZE_WHITESPACE
      Help on getset descriptor System.Collections.Generic in mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089.Enumerator.Current:
          Get: T Current(self)
    • Extensions to Python types

      import clr exposes extra functionality on some Python types to make .NET features accessible:

      • method objects of any builtin or .NET types:
        • instance method
          • Overloads(t1 [, t2...])
      • type objects
        • instance method
          • __getitem__(t1 [, t2...]) - creates a generic instantiation


Using COM objects

One you have access to a COM object, it can be used like any other objects. Properties, methods, default indexers and events all work as expected.



Methods with ref or out parameters


python重写的办法时原来传出的特别参数群集中最终一个活动被定义为一个CL奥迪Q5引用类型,调用方法后,读取这一个指标的值就能够收获输出结果,相通,在重写方法的进度中,大家也非得以  参数名.Value的花样给那个CLHighlander引用类型的变量赋值

Python does not have syntax for specifying whether a method paramter is passed by-reference since arguments are always passed by-value. When overriding a .NET method with ref or out parameters, the ref or out paramter is received as a clr.Reference[T] instance. The incoming argument value is accessed by reading theValue property, and the resulting value is specified by setting the Value property:

>>> import clr
>>> import System
>>> StrFloatDictionary = System.Collections.Generic.IDictionary[str, float]
>>> class MyDictionary(StrFloatDictionary):
...     def TryGetValue(self, key, value):
...         if key == "yes":
...             value.Value = 100.1 # set the *out* parameter
...             return True
...         else:
...             value.Value = 0.0  # set the *out* parameter
...             return False
...     # Other methods of IDictionary not overriden for brevity
>>> d = MyDictionary()
>>> # Use Reflection to simulate a call from another .NET language
>>> tryGetValue = clr.GetClrType(StrFloatDictionary).GetMethod("TryGetValue")
>>> args = System.Array[object](["yes", 0.0])
>>> tryGetValue.Invoke(d, args)
>>> args[1]

In the explicit way, you can pass an instance of clr.Reference[T] for the ref or out argument, and its Value field will get set by the call. The explicit way is useful if there are multiple overloads with ref parameters:

This is an implementation detail.

>>> BitArray((1, 2, 3))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Multiple targets could match: BitArray(Array[Byte]), BitArray(Array[bool]), BitArray(Array[int])
>>> from System.Collections import BitArray
>>> isinstance(ba, BitArray)


Non-automation COM objects

IronPython does not fully support COM objects which do not support dispinterfaces since they appear likey proxy objects [12]. You can use the unbound class method syntax to access them.

[12] This was supported in IronPython 1, but the support was dropped in version 2.



The unification also extends to other type system entities like methods. .NET methods are exposed as instances of method:



.NET supports overloading methods by both number of arguments and type of arguments. When IronPython code calls an overloaded method, IronPython tries to select one of the overloads at runtime based on the number and type of arguments passed to the method, and also names of any keyword arguments. In most cases, the expected overload gets selected. Selecting an overload is easy when the argument types are an exact match with one of the overload signatures:

Note that if you import a static property, you will import the value when the import executes, not a named object to be evaluated on every use as you might mistakenly expect:

>>> SpecialFolder is System.Environment.SpecialFolder

Creating a COM object


Different languages have different ways to create a COM object. VBScript and VBA have a method called CreateObject to create an OleAut object. JScript has a method called TODO. There are multiple ways of doing the same in IronPython.

  1. The first approach is to use System.Type.GetTypeFromProgID and System.Activator.CreateInstance . This method works with any registered COM object:

    >>> import System
    >>> t = System.Type.GetTypeFromProgID("Excel.Application")
    >>> excel = System.Activator.CreateInstance(t)
    >>> wb = excel.Workbooks.Add()
    >>> excel.Quit()
  2. The second approach is to use clr.AddReferenceToTypeLibrary to load the type library (if it is available) of the COM object. The advantage is that you can use the type library to access other named values like constants:

    >>> import System
    >>> excelTypeLibGuid = System.Guid("00020813-0000-0000-C000-000000000046")
    >>> import clr
    >>> clr.AddReferenceToTypeLibrary(excelTypeLibGuid)
    >>> from Excel import Application
    >>> excel = Application()
    >>> wb = excel.Workbooks.Add()
    >>> excel.Quit()
  3. Finally, you can also use the interop assembly. This can be generated using the tlbimp.exe tool. The only advantage of this approach was that this was the approach recommeded for IronPython 1. If you have code using this approach that you developed for IronPython 1, it will continue to work:

    >>> import clr
    >>> clr.AddReference("Microsoft.Office.Interop.Excel")
    >>> from Microsoft.Office.Interop.Excel import ApplicationClass
    >>> excel = ApplicationClass()
    >>> wb = excel.Workbooks.Add()
    >>> excel.Quit()
>>> import System
>>> System.ICloneable.Clone("hello") # same as : "hello".Clone()

See appendix for the detailed rules.

Properties with parameters

COM and VB.NET support properties with paramters. They are also known as non-default indexers. C# does not support declaring or using properties with parameters.

IronPython does support properties with parameters. For example, the default indexer above can also be accessed using the non-default format as such:

>>> ba.Item[0]

.net的事件能够行使 = 和-=的样式开展注册和卸载,在IronPython中相近支撑这种耍法,上边包车型地铁代码里用python 代码遵照.Net的格式定义了叁个回调函数,居然也能注册到.Net事件里去,真爽

.NET events are exposed as objects with __iadd__ and __isub__ methods which allows using  = and -= to subscribe and unsubscribe from the event. The following code shows how to subscribe a Python function to an event using  =, and unsubscribe using -=

>>> from System.IO import FileSystemWatcher
>>> watcher = FileSystemWatcher(".")
>>> def callback(sender, event_args):
...     print event_args.ChangeType, event_args.Name
>>> watcher.Created  = callback
>>> watcher.EnableRaisingEvents = True
>>> import time
>>> f = open("test.txt", "w "); time.sleep(1)
Created test.txt
>>> watcher.Created -= callback
>>> # cleanup
>>> import os
>>> f.close(); os.remove("test.txt")

You can also subscribe using a bound method:


>>> watcher = FileSystemWatcher(".")
>>> class MyClass(object):
...     def callback(self, sender, event_args):
...         print event_args.ChangeType, event_args.Name
>>> o = MyClass()
>>> watcher.Created  = o.callback
>>> watcher.EnableRaisingEvents = True
>>> f = open("test.txt", "w "); time.sleep(1)
Created test.txt
>>> watcher.Created -= o.callback
>>> # cleanup
>>> f.close(); os.remove("test.txt")

You can also explicitly create a delegate instance to subscribe to the event. Otherwise, IronPython automatically does it for you. [4]:


>>> watcher = FileSystemWatcher(".")
>>> def callback(sender, event_args):
...     print event_args.ChangeType, event_args.Name
>>> from System.IO import FileSystemEventHandler
>>> delegate = FileSystemEventHandler(callback)
>>> watcher.Created  = delegate
>>> watcher.EnableRaisingEvents = True
>>> import time
>>> f = open("test.txt", "w "); time.sleep(1)
Created test.txt
>>> watcher.Created -= delegate
>>> # cleanup
>>> f.close(); os.remove("test.txt")


The only advantage to creating an explicit delegate is that it is uses less memory. You should consider it if you subscribe to lots of events, and notice excessive System.WeakReference objects.



IronPython supports indexing of System.Array with a type object to access one-dimensional strongly-typed arrays:

>>> System.Array[int]
<type 'Array[int]'>

IronPython also adds a __new__ method that accepts a IList<T> to initialize the array. This allows using a Python list literal to initialize a .NET array:

>>> a = System.Array[int]([1, 2, 3])

Further, IronPython exposes __getitem__ and __setitem__ allowing the array objects to be indexed using the Python indexing syntax:

>>> a[2]


Note that the indexing syntax yields Python semantics. If you index with a negative value, it results in indexing from the end of the array, whereas .NET indexing (demonstrated by calling GetValue below) raises a System.IndexOutOfRangeException exception:

>>> a.GetValue(-1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: Index was outside the bounds of the array.
>>> a[-1]

如出后生可畏辙也支持python 中的数组分割语法

Similarly, slicing is also supported:

>>> a[1:3]
Array[int]((2, 3))
Python argument type .NET method parameter type
int System.Int8, System.Int16
float System.Float
tuple with only elements of type T System.Collections.Generic.IEnumerable<T>
function, method System.Delegate and any of its sub-classes

Hashing of mutable objects

The CLR expects that System.Object.GetHashCode always returns the same value for a given object. If this invariant is not maintained, using the object as a key in a System.Collections.Generic.Dictionary<K,V> will misbehave. Python allows __hash__ to return different results, and relies on the user to deal with the scenario of using the object as a key in a Hash. The mapping above between the Python and CLR concepts of equality and hashing means that CLR code that deals with Python objects has to be aware of the issue. If static MSIL code uses a Python object as a the key in a Dictionary<K,V>, unexpected behavior might happen.

To reduce the chances of this happenning when using common Python types, IronPython does not map __hash__ to GetHashCode for Array and Hash. For other Python classes, the user can provide separate implementations for __eq__ and Equals, and __hash__ and GetHashCode if the Python class is mutable but also needs to be usable as a key in a Dictionary<K,V>.


In the implicit way, an argument is passed normally to the method call, and its (potentially) updated value is returned from the method call along with the normal return value (if any). This composes well with the Python feature of multiple return values. System.Collections.Generic.Dictionary has a method bool TryGetValue(K key, out value). It can be called from IronPython with just one argument, and the call returns a tuple where the first element is a boolean and the second element is the value (or the default value of 0.0 if the first element is False):

The unbound class instance method syntax results in a virtual call, and calls the most derived implementation of the virtual method slot:

>>> from Microsoft.Win32 import Registry
>>> rkey = Registry.CurrentUser.OpenSubKey("Software")
>>> rkey.Dispose()
>>> System.GC.Collect()



.NET enumeration types are sub-types of System.Enum. The enumeration values of an enumeration type are exposed as class attributes:

print System.AttributeTargets.All # access the value "All"

IronPython also supports using the bit-wise operators with the enumeration values:

也协助 位操作符

>>> import System
>>> System.AttributeTargets.Class | System.AttributeTargets.Method
<enum System.AttributeTargets: Class, Method>

The argument types do not have be an exact match with the method signature. IronPython will try to convert the arguments if an unamibguous conversion exists to one of the overload signatures. The following code calls __new__(System.Int32) even though there are two constructors which take one argument, and neither of them accept a float as an argument:

>>> from System.Collections import BitArray
>>> ba = BitArray(5) # calls __new__(System.Int32)
>>> ba = BitArray(5, True) # calls __new__(System.Int32, System.Boolean)
>>> ba = BitArray(ba) # calls __new__(System.Collections.BitArray)

Calling base constructor



.NET constructors can be overloaded. To call a specific base type constructor overload, you need to define a __new__ method (not __init__) and call __new__ on the .NET base type. The following example shows how a sub-type of System.Exception choses the base constructor overload to call based on the arguments it receives:

>>> import System
>>> class MyException(System.Exception):
...     def __new__(cls, *args):
...        # This could be implemented as:
...        #     return System.Exception.__new__(cls, *args)
...        # but is more verbose just to make a point
...        if len(args) == 0:
...            e = System.Exception.__new__(cls)
...        elif len(args) == 1:
...            message = args[0]
...            e = System.Exception.__new__(cls, message)
...        elif len(args) == 2:
...            message, inner_exception = args
...            if hasattr(inner_exception, "clsException"):
...               inner_exception = inner_exception.clsException
...            e = System.Exception.__new__(cls, message, inner_exception)
...        return e
>>> e = MyException("some message", IOError())
>>> args = [2, True] # list of arguments
>>> ba.Set(*args)
>>> ba[2]



Starting with .NET 4.0, C# and VB.Net support access to IronPython objects using the dynamic keyword. This enables cleaner access to IronPython objects. Note that you need to use the hosting-apis to load IronPython code and get the root object out of it.

However, properties are not imported:

TODO - Example of indexing Overloads with an Array, byref, etc using Type.MakeByrefType

Declaring .NET types


Just like with normal Python modules, you can also use all the other forms of import as well:

Extensions to .NET types


IronPython also adds extensions to .NET types to make them more Pythonic. The following instance methods are exposed on .NET objects (and .NET classes where explicitly mentioned):

  • Types with op_Implicit

    • TODO
  • Types with op_Explicit

    • TODO
  • Types inheriting from a .NET class or interface

    .NET base-type

    Synthesized Python method(s)


    all methods of object eg. __class__, __str__, __hash__, __setattr__


    __enter__, __exit__



    System.Collections.ICollection System.Collections.Generic.ICollection<T>


    System.Collections.IEnumerable System.Collections.Generic.IEnumerable<T> System.Collections.IEnumerator System.Collections.Generic.IEnumerator<T>




    System.Collections.IDictionary System.Collections.Generic.IDictionary<TKey, TValue> System.Collections.Generic.ICollection<T> System.Collections.Generic.IList<T> System.Collections.IEnumerable System.Collections.Generic.IEnumerable<T> System.Collections.IEnumerator System.Collections.Generic.IEnumerator<T>



    • Class methods:
      • Indexing of the type object with a type object to access a specific array type
      • __new__(l) where l is IList<T> (or supports __getitem__?)
    • __getitem__, __setitem__, __slice__


    • Class method : __new__(type, function_or_bound_method)
    • __call__


    __or__ TODO ?

  • Types with a .NET operator method name

    .NET operator method

    Synthesized Python method

    op_Addition, Add




    get_<Name> [8]


    set_<Name> [9]


[8] where the type also has a property <Name>, and a DefaultMemberAttribute for <Name>
[9] where the type also has a property <Name>, and a DefaultMemberAttribute for <Name>



>>> args = { "index" : 3, "value" : True }
>>> ba.Set(**args)
>>> ba[3]

IronPython also supports keyword arguments:

>>> from System.DateTime import Now
>>> Now #doctest:  ELLIPSIS
<System.DateTime object at ...>
>>> # Let's make it even more obvious that "Now" is evaluated only once
>>> a_second_ago = Now
>>> import time
>>> time.sleep(1)
>>> a_second_ago is Now
>>> a_second_ago is System.DateTime.Now


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