[Kde-bindings] KDE/kdebindings/csharp/qyoto

[Arno Rehn]

On Tuesday 17 February 2009 22:22:32 Arno Rehn wrote:
> SVN commit 927583 by arnorehn:
>
> * Add support for C# events. They're called Signal<signalName> and if
> they're overloaded, additionally have their arguments attached to their
> name. This should be considered highly experimental and can change at any
> time.
As there was some discussion about this on IRC, now here's what I think:
We should provide some alternative to the traditional Connect() method of Qt 
to connect signals to slots; something that feels more C#ish, or better, .NET-
ish. The most obvious possibility to do this is C# events and that's what I 
recently checked in. With it you can connect a delegate, i.e. anonymous 
function, lambda function or simply a method to a signal, like this:

	MyButton.SignalClicked += delegate(bool clicked) { /* do stuff */ };

or
	MyButton.SignalClicked += SlotMethod;

Disconnecting happens with the -= operator. This approach currently has some 
downsides, like you can't overload events and need to give them ugly names 
because of that. Also we'd need to decide whether we want to use the .NET 
pattern for the delegates, which would basically result in a special delegate 
for each signal in the form of

void Delegate(object sender, Arguments objectContainingTheArguments)

Personally I think the .NET pattern is crap. Why have a special class for each 
signal that contains all the arguments of the signal? It kinda eliminates the 
purpose of method parameters if you have to store them in another object 
anyway. Regarding the first "sender" parameter: we can access that through 
QObject.Sender() so it's not really needed here either.
As Richard said, we should create something that's better than GTK#. And I 
think it's better to keep it the 'Qt'-way and pass every signal parameter 
directly. This also eases writing short anonymous/lambda functions if you have 
all the parameters that you need readily at hand.
And as we are at it: A better way to handle Qt signals would be to add methods 
like AddClickedHandler() which take a delegate, similar to an event. But you 
can overload methods and that would get rid of the need for ugly event names.
Plus I dislike the += and -= syntax, so imho it'd be optically nicer as well 
:).

Maybe I commited my changes to early, sorry about that. But it's just one 
commit and it can be reverted easily I guess - in case there's a need for it.

-- 
Arno Rehn
arno at arnorehn.de