Invoke object methods with a symbolic reference

sguazt has asked for the wisdom of the Perl Monks concerning the following question:

If you have this perl code:

package Foo;
use strict;

sub new { return bless {f => 'foo'}, $_[0]; }
sub foo { shift; print "@_\n"; }
1;

package main;
use strict;

my $a = new Foo();

my $f = $a->{f};
no strict qw(subs);
$a->$f('foobar');

1;
__END__
[download]

I would like invoke 'foo' method in a more compress form, such as:

$a->${$a->{f}}('foobar');
[download]

but this latter form doesn't work!!

Any idea???

Comment on Invoke object methods with a symbolic reference Select or Download Code

Replies are listed 'Best First'.
Re: Invoke object methods with a symbolic reference by mirod (Canon) on Feb 14, 2001 at 18:13 UTC
I don't quite get the compactness of `$a->${$a->{f}}('foobar');` but maybe what you are loking for is to store a reference to the `foo` method instead of its name: `sub new { return bless {f => \&foo}, $_[0]; } # \&foo is a reference to foo()` And then you can call the subroutine (including under `use strict`) as `$a->{f}('foobar');` just note that in this case `foo` is just a regular function, not a method any more and you either have to remove the `shift` in the function or pass it `$a`.	[reply] [d/l] [select]
Rea: Invoke object methods with a symbolic reference by baku (Scribe) on Feb 14, 2001 at 19:59 UTC
You could do the same by generating a closure to pass it `$a == $self`: `sub new { my $self = {}; bless $self, $_[0]; $self->{f} = sub { &foo ($self, @_); }; return $self; }` [download] The only reason for the three-line form with temporary variable is that I can't figure out how else to embed the closure "reference" to the object (`$self`) inside of an hash inside of the object itself :-) (fixed minor typo!)	[reply] [d/l] [select]
Re: Invoke object methods with a symbolic reference by merlyn (Sage) on Feb 14, 2001 at 19:51 UTC
It doesn't work because the symbolic invocation format isn't fully orthogonal. You could do something like this instead: `$a->can($a->{f})($a, 'foobar');` [download] But I don't know if that's any better than what you have. By the way, you don't need `no strict subs`, since this isn't considered a symbolic reference. In fact, `no strict subs` deals with barewords: not even related here! -- Randal L. Schwartz, Perl hacker	[reply] [d/l]