Re: Stealing a good idea from Gtk#

[muppet <scott asofyet org>]

On Sep 26, 2004, at 8:00 PM, A. Pagaltzis wrote:

> * Torsten Schoenfeld <kaffeetisch gmx de> [2004-09-26 23:45]:
> >   $button -> Clicked += \&clicked;

i presume you would disconnect a signal with the -= operator?


> It's definitely cool. Three things irk me, though:
>
>     a) += just isn't used that way in Perl, and I think
>        overloading its meaning the way its done here is too
>        idiosyncratic.

less politely, it reeks of the operator overloading abuse that commonly 
afflicts C++/C# people.  =)

what irks me the most about it is that, yes it's true that you're 
adding a handler to the signal, but you're not doing a += operation.  a 
+= b makes sense where both a and b are "Foo"s.  seen in that light, 
something like

  <signal> += <handler>

makes less sense.  say you wanted to get the id from that connection.  
you'd now have

  <id> = <signal> += <handler>

which makes even *less* sense.  shouldn't the resulting value of 
Foo+=something still be a Foo?



> As far as a) is concerned, the really Perlish way would of course
> be a tied array that you can push subrefs onto and delete from...
> but ehm, that would be overengineered. :)

(and, actually, impossible.  you can find out if there are handlers 
connected, and you can block and disconnect, but you can't *list* the 
handlers of a signal on a given instance.)


> I'm thinking the operator should be a simple assignment, in which
> case you can switch from overload to a tied interface, too.

in defense of the += operator, the += makes sense because you can 
connect any number of handlers to a signal, while = implies a 
Highlander nature ("there can be only one!").


how would you handle variants like connect-after and user data?  the 
obvious thing to come to mind is (using Aristotle's naming because 
StudlyCaps suck)

  $window->SIGNAL::delete_event += { handler=>\&my_delete, data 
=>$thing, after => TRUE };
  $window->SIGNAL::delete_event -= { handler=>\&my_delete, data 
=>$thing };

but by comparison with

  $window->signal_connect_after (delete_event => \&my_delete, $thing);
  $window->signal_handlers_disconnect_by_func (\&my_delete, $thing);

the cool hack way is, well, rather a bit more verbose.


so, i must say i don't like the cool hack, even though it is an 
impressive and very cool hack.


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