In gtkD one can use a lambda directly:
X.addOnButtonPress((GdkEventButton* e, Widget w) ...
but if I try move the lambda in to a variable so I can use it
with multiple handlers, I get an error:
// x is a function and does not work
auto x = (GdkEventButton* e, Widget w) ...
X.addOnButtonPress(x);
etc...
It's because the second case treats x as a function while the
first it is a delegate and addOnButtonPress requires a delegate...
Why is x not a delegate?
Now, if I reference a variable outside the scope of the lambda it
turns magically in to a delegate and works!
But that is an ugly hack!
// now x is a delegate and works
auto x = (GdkEventButton* e, Widget w) { auto q = X; ...
Now sure I can hack x and use some template to turn it in to a
fake delegate but then that is dangerous.
I suppose one could have a template that only converts it if it
is a function and then that will deal with both cases and might
work...
But why?
Is there any way to force it to not reduce the delegate to a
function which is obviously an optimization when nothing accesses
the outside context.
