You can define an extension property that gets/sets a value which supports in
place addition / subtraction. Something like this:
[assembly: ExtensionType(typeof(HtmlElement), typeof(HtmlElementExtension))]
public static class HtmlElementExtension {
[SpecialName, PropertyMethod]
public static MyEvent Getonclick(HtmlElement element) {
return new MyEvent(element);
}
[SpecialName, PropertyMethod]
public static void Setonclick(HtmlElement element, object value) {
// You could return a value from InPlaceAdd and validate it here
// to report an error on a direct assignment - this is what
// ReflectedEvent does in IronPython.
}
}
public class MyEvent {
private readonly HtmlElement _element;
public MyEvent(HtmlElement element) {
_element = element;
}
[SpecialName]
public object InPlaceAdd(EventHandler[HtmlEventArgs] handler) {
_element.AttachEvent("onclick", handler);
return null;
}
// also needs InPlaceSubtract
}
-----Original Message-----
From: users-boun...@lists.ironpython.com
[mailto:users-boun...@lists.ironpython.com] On Behalf Of Jimmy Schementi
Sent: Sunday, February 14, 2010 2:06 PM
To: Discussion of IronPython
Subject: [IronPython] Monkey-patching CLR types
(Yes, I'm asking a question this time =P)
I want to know my options for adding functionality to an existing CLR type.
Specifically I want to make hooking DOM events cleaner: in Silverlight today
you cannot hook DOM events with the standard += syntax that IronPython uses for
CLR events:
object.onclick += foo
Instead you must do this:
object.AttachEvent("onclick", EventHandler[HtmlEventArgs](foo))
In IronRuby I fixed that by just monkey-patching
System.Windows.Browser.HtmlObject, but in IronPython I cannot monkey-patch
built-in types. However, I do something similar with accessing DOM properties
(instead of element.GetProperty("innerHTML") it's just element.innerHTML) with
DLR's ExtensionType, which is the same way IronPython exposes special methods
on CLR types as well:
[assembly: ExtensionType(typeof(HtmlElement), typeof(HtmlElementExtension))]
public static class HtmlElementExtension {
[SpecialName]
public static object GetBoundMember(HtmlElement element, string name) {
return element.GetProperty(name);
}
}
But after looking through Python's Binder and the DLR's ActionBinder for how
they use ExtensionTypes, I couldn't get a definitive answer on how to capture
an method call plus an operator. Any ideas?
~Jimmy
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