Re^3: SDLx handlers and Moose


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Re^3: SDLx handlers and Moose

by Mr. Muskrat (Canon)

on May 25, 2012 at 17:53 UTC ( [id://972508]=note: print w/replies, xml )

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in reply to Re^2: SDLx handlers and Moose
in thread SDLx handlers and Moose

A callback is a reference to a function. If you put a method call where a callback is needed, it won't work as expected.

# The first one is wrong. It adds a reference to an subroutine named f
+or the return value of $ship->move (or \&1) 
# because print returns 1 when it is successful.
$app->add_move_handler ( \&{$ship->move} ); 

$app->add_move_handler ( sub { $ship->move( @_ ) } );
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Try this to verify that:

#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Deparse = 1;

use Mob;

my $ship = Mob->new();

my $first = \&{$ship->move};
print "first: ", Dumper( $first );

my $second = sub { $ship->move( @_ ) };
print "second: ", Dumper( $second );

# &$first(); # Uncomment to see the error 'Undefined subroutine &main:
+:1 called at ./test.pl line 17.'

&$second( 1, 2 );
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Update: chromatic replied while I was typing this up with more thorough answers than mine.