RE: [tcltk-perl] Change the way that %-subs are handled.

[Konovalov, V. <vko...@sp...>]

> I finally figured out the magic that makes the commands that
> require %-substitutions to work, like so:
> 
>      my $sub = sub {
> 	my ($X, $Y) = (Tcl::Ev('X'), Tcl::Ev('Y'));
> 	print "X: $X Y: $Y\n";
>      };
>      $mw->bind('<Motion>', \\'XY', $sub);
> 
> This double-reference to the scalar seems a little weird to me.

"weirdness" is clearly stated inside Tcl.pm.
This is documented, hence is not a bug :)

But seriously I also dislike \\'XY'


> It would of course be best if we could somehow manage to get the
> substitutions as part of the command.
> 
> Now that we properly handle command callbacks with args, I would
> like to recommend this alternative:
> 
>      $mw->bind('<Motion>', [$sub, Tcl::EV('X', 'Y', ...), 
> "foo", ...]);
> 
> This would magic convert to the either the same special things
> that requires the Tcl::Ev in the sub, or perhaps (if I can make
> the magic work), have it pass the %-subs to the Tcl side of the
> callback, while maintaining the "foo", ... for the perl side.
> 
> Any objections, or better ideas?

I still hope that "correct" method is doable, namely

    $mw->bind('<Motion>', \&hadler), 
    sub handler {
      # uses %-subs freely, 
      print Ev('x');
    }

I thought this is quite doable with Ev to do some preparations first (to
manage which results must be stored), and then return an object that, at a
time when its result is needed, retreives it properly.

I remember this could lead to complications, but still I have a feeling that
is is doable.

BTW, probably right now it is the right moment to check how this is
implemented in Ruby or Python.


Vadim.