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Re^8: How can I call a Perl sub with an object from a sub name stored in a var?

by LanX (Saint)
on Dec 10, 2020 at 11:39 UTC ( #11124950=note: print w/replies, xml ) Need Help??


in reply to Re^7: How can I call a Perl sub with an object from a sub name stored in a var?
in thread How can I call a Perl sub with an object from a sub name stored in a var?

> Any defined-but-non-coderef value is stringified

Correction: any "non-coderef value is stringified" , even undef is stringified to an empty string. ( It's just tricky to create a sub for an empty symbol. :)

DB<199> $obj = bless {},"tmp" DB<200> $tmp::{''} = sub { say "empty" } DB<201> $meth = undef DB<202> $obj->$meth empty DB<203>

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

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Re^9: How can I call a Perl sub with an object from a sub name stored in a var?
by tobyink (Canon) on Dec 10, 2020 at 12:05 UTC

    I did try undef, but got warnings, so figured it was verboten. I ought to have continued with my experiments.

    Here's something fun. Acme::Ref breaks on recent Perls, but it's a one line patch to fix it. (The _deref function needs to take a long argument instead of an int.)

    use strict; use warnings; use feature 'say'; { package Local::Class; sub new { my ( $class ) = ( shift ); bless {}, $class; } sub AUTOLOAD { my ( $method ) = ( our $AUTOLOAD =~ /([^:]+)$/ ); if ( $method =~ /^(ARRAY|HASH|SCALAR|REF)/i ) { require Acme::Ref; my $real_coderef = $_[0]->can("HANDLE_$1") or die "Cannot handle $1 method"; splice @_, 1, 0, do { local $SIG{__WARN__} = sub {}; Acme: +:Ref::deref($method); }; goto $real_coderef; } return if $method eq 'DESTROY'; die "Could not load $method via AUTOLOAD"; } sub HANDLE_ARRAY { my ( $self, $array, @args ) = ( shift, shift, @_ ); say for @$array; } sub HANDLE_HASH { say "whatever"; } # etc... }; my $object = 'Local::Class'->new(); my $array = [ "Hello", "world" ]; $object->$array; $object->${\ [ "And", "again" ] };

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