Bug #17008 for UNIVERSAL-can: can breaks exceptions, like $@->can

Tue Jan 10 12:03:44 2006 Guest - Ticket created

Subject:

can breaks exceptions, like $@->can

Below a two perl snippets, equal to each other, except for the usage of UNIVERSAL::isa. They are all valid method calls of can. however with UNIVERSAL::isa the calll dies. perl -wle 'use strict; eval { die bless {}, "main" }; print $@->can("x")' perl -wle 'use UNIVERSAL::can; use strict; eval { die bless {}, "main" }; print $@->can("x")' and a workaround: perl -wle 'use UNIVERSAL::can; use strict; eval { die bless {}, "main" }; my $a=$@; print $a->can("x")' Enviroment is freebsd, and perl 5.8.7 This is due to UNIVERSAL::can does not make a copy of $_[0], but works on the callers copy. In this case $@. Then can calls eval itself, $@ will be empty, and so will $_[0]. Solution: Either make a copy of $@. Or try to do a "local $@" before the eval?

Tue Jan 10 12:35:53 2006 Guest - Correspondence added

Subject:	patch [can breaks exceptions, like $@->can]
From:	Martin

The following patch works for me *** UNIVERSAL/can.pm --- UNIVERSAL/can.pm *************** *** 25,33 **** goto &$orig if $recursing; goto &$orig unless _is_invocant( $_[0] ); ! my $can = eval { $_[0]->$orig( 'can' ) || 0 }; goto &$orig if $can == \&UNIVERSAL::can; local $recursing = 1; my $invocant = shift; --- 25,34 ---- goto &$orig if $recursing; goto &$orig unless _is_invocant( $_[0] ); ! my $can; ! { local $@; $can = eval { $_[0]->$orig( 'can' ) || 0 }; }; goto &$orig if $can == \&UNIVERSAL::can; local $recursing = 1; my $invocant = shift;

Tue Jan 10 20:04:13 2006 chromatic [...] cpan.org - Correspondence added 10 min

Good catch. Fixed in 1.02, which should be on the CPAN in a few minutes.

Tue Jan 10 20:04:14 2006 chromatic [...] cpan.org - Status changed from 'new' to 'resolved'

Tue Jan 10 20:04:15 2006 chromatic [...] cpan.org - Given to CHROMATIC