By the way, I fixed this by just overloading the "+" operator the normal way C#
operators are overloaded, had it accept "object" on the right-hand-side so
Python functions would make their way into it, and then used
ObjectOperations.ConvertTo to convert the Python function to a
System.EventHandler.
From: Jimmy Schementi
Sent: Tuesday, February 16, 2010 12:09 AM
To: Discussion of IronPython
Subject: RE: Monkey-patching CLR types
Dino Viehland wrote:
> If you strongly type handler to a delegate type IronPython should convert the
> function to the delegate type on the call.
Unfortunately it doesn't seem to :(. I repro'd that it doesn't on the desktop
as well as in Silverlight; here's a desktop repro:
>>> import clr
>>> clr.AddReferenceToFile("pyext")
>>> import pyext
>>> t = pyext.TestClass()
>>> def foo(s, e): pass
...
>>> import System
>>> t.AttachEvent("foo", System.EventHandler(foo))
foo hooked!
>>> t.foo += foo
Traceback (most recent call last):
File "<stdin>", line unknown, in <module>
TypeError: unsupported operand type(s) for +=: 'MyEvent' and 'function'
Also, when using a EventHandler as the right-hand-side of the +=, the
AttachEvent method gets called, but still complains that the "foo" attribute
doesn't exist:
>>> t.foo += System.EventHandler(foo)
foo hooked!
Traceback (most recent call last):
File "<stdin>", line unknown, in <module>
AttributeError: 'TestClass' object has no attribute 'foo'
Any ideas? Here's the pyext.cs stub that I used:
//
// pyext.cs
//
using Microsoft.Scripting.Runtime;
using System;
using Microsoft.Scripting.Utils;
using System.Runtime.CompilerServices;
[assembly: ExtensionType(typeof(pyext.TestClass),
typeof(pyext.TestClassExtension))]
namespace pyext {
public class TestClass {
public void AttachEvent(string eventName, EventHandler handler) {
Console.WriteLine(string.Format("{0} hooked!", eventName));
}
}
public static class TestClassExtension {
[System.Runtime.CompilerServices.SpecialNameAttribute]
public static object GetBoundMember(TestClass obj, string name) {
return new MyEvent(obj, name);
}
}
public class MyEvent {
private readonly TestClass _obj;
private readonly string _event;
internal MyEvent(TestClass obj, string eventStr) {
_obj = obj;
_event = eventStr;
}
[System.Runtime.CompilerServices.SpecialNameAttribute]
public object op_AdditionAssignment(EventHandler func) {
_obj.AttachEvent(_event, func);
return null;
}
}
}
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