Howto set event handlers with arbitrary type with RTTI in Delphi 2010?
after reading the post How to set event handlers via new RTTI?, I wonder if it is possible to solve this more dynamically. For example I want to set ALL event handlers of any component to nil.
Using TValue.From <TNotifyEvent> (SomeMethod)
does not work for two reasons:
1. The type is unknown (could be TNotifyEvent, TMouseEvent etc.)
2. I cannot set 'SomeMethod' to nil (invalid cast)
In old RTTI style I would do something like:
var
开发者_StackOverflow中文版NilMethod: TMethod;
begin
[...]
NilMethod.Data := nil;
NilMethod.Code := nil;
SetMethodProp (AComponent,PropertyName,NilMethod);
The following code ought to work:
procedure NilAllEventHandlers(myObject: TObject);
var
context: TRttiContext;
rType: TRttiType;
field: TRttiField;
value: TValue;
nilMethod: TMethod;
begin
nilMethod.Code := nil;
nilMethod.Data := nil;
context := TRttiContext.Create;
rType := context.GetType(TButton);
for field in rType.GetFields do
begin
if field.FieldType.TypeKind = tkMethod then
begin
TValue.Make(@nilMethod, field.FieldType.Handle, value);
field.SetValue(myObject, value);
end;
end;
end;
But it doesn't because there's a bug in TValue.TryCast when working with a TMethod value whose .Code parameter is nil. I'll report it to QC. Hopefully it'll get fixed in D2011 or an update. Until then, try the old style.
EDIT: Reported as QC# 81416. Vote it up if you want to see it fixed.
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