in reply to Question re $obj->$action(@args) syntax

As I said above, not that I really need this "feature", but is there a way to "inline" a subref as hinted above? Somehow it strikes me as as something that should be doable if not for anything else for completeness sake...

This topic comes up from time to time on p5p. The short answer is that while theoretically it makes sense from some sort of orthogonal point of view, the parser code is not particularly amenable in this respect. From memory it's got something to do with disambiguating curlies (is this a hash deref or a code block coming up).

That said, you can inline a subref lookup, if you are brave and insist on this approach. Given the package:

package Foo; sub new { bless { val => $_[1] }, $_[0]; } sub zug { my $self = shift; my $arg = shift; return "$arg $self->{val} $arg"; } sub zwang { my $self = shift; my $arg = shift; return join( ' ', ($self->{val}) x $arg ); }

Then the tradtional as-per-perlop approach would be:

my $f = Foo->new('doot'); my @meth = (qw(zug zwang)); # doesn't work: # print $f->$meth[rand @meth](3); my $m = $meth[rand @meth]; print $f->$m(3), $/;

But you can avoid creating the intermediate lexical by dereferencing a scalar reference:

my $f = Foo->new('doot'); # update: with subrefs: my @meth = (\&Foo::zug, \&Foo::zwang); print $f->${\$meth[rand @meth]}(3);

But you have to admit that the traditional approach is a little easier for people to comprehend.

updated: added an initialistion to show that the code works with true coderefs as well as bareword method names.

• another intruder with the mooring in the heart of the Perl

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Re^2: Question re $obj->$action(@args) syntax
by blazar (Canon) on Mar 21, 2007 at 15:00 UTC
    This topic comes up from time to time on p5p. The short answer is that while theoretically it makes sense from some sort of orthogonal point of view, the parser code is not particularly amenable in this respect. From memory it's got something to do with disambiguating curlies (is this a hash deref or a code block coming up).

    That is exactly what I had in mind: orthogonality and consistency. (Well, Perl 5 already deviates from them whenever convenient, and in very useful ways, so I'm not going mad about them either, but... well... you know...) And that's what I expected too: parsing difficulties.

    That said, you can inline a subref lookup, if you are brave and insist on this approach.

    Thank you for the suggestion. It is exactly the kind of trick I insistently thought that ought to exist:

    #!/usr/bin/perl use strict; use warnings; use Data::Dumper; (bless {}, 'Foo')->${\sub { print Dumper \@_ }}(1,2,3); __END__

    Which is strange, because I made some tests and I was quite sure to have tried something along these lines too. Probably there were some spurious error that made me infer the wrong conclusion.

    But you have to admit that the traditional approach is a little easier for people to comprehend.

    Oh, for that... seconded all the way!