minigui docs: event handler must be a delegate

[whitebyte]

https://dpldocs.info/experimental-docs/arsd.minigui.Event.html

Trying to actually compile an example from this page

widget.addEventListener((KeyDownEvent ev) { ... }, /* optional arg */ useCapture );

throws arsd/minigui.d(1416): Error: static assert: "Your handler wasn't usable because it wasn't passed a delegate. Use the delegate keyword at the call site."

Marking lambda as a delegate solves the issue:

widget.addEventListener(delegate(KeyDownEvent ev) { ... }, /* optional arg */ useCapture );

no biggie but it's worth mentioning in the docs. Also, useCapture isn't documented anywhere

[adamdruppe]

yeah if you use local variables it is automatically a delegate so in most cases it will work but an empty function (or just a writeln logger) won't.

useCapture means the event is triggered on the capture phase instead of the bubble phase. the docs talk about this but it is mostly a javascript thnig you can look up too

maybe ill rewrite that soon

[whitebyte]

it will work but an empty function (or just a writeln logger) won't.

That was exactly my case. I just slapped a writeln to check if it works. Then why minigui insists on a delegate? If a programmer is ok with a plain function that doesn't capture context, minigui should also be ok

[adamdruppe]

It just requires adding like 12 function overloads for the function to delegate adapters.... easier to just put the word at the call site lol

[adamdruppe]

OpenD could probably implicitly convert function to delegate, codegen wise you can do it and there's no loss of information (you can do it in library too, put a thunk in the funcptr then ptr is the actual funcptr). So solid maybe putting that right in the compiler but might also cause side effects.