Unexpected compiler behavior

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

Does anybody can explain why "require BB;" in 1.pl don't work in this case:

--------------------------------- file 1.pl

#!/usr/bin/env perl

use 5.18.2;

$SIG{__WARN__} = sub {
    say qq{WARN: $_[0]};
    require BB;
};

require AA;

1;
__END__
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--------------------------------- file AA.pm

package AA;

use warnings;

a b

sub aa {
    my $self = shift;
    
    return $self;
}

1;
__END__
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--------------------------------- file BB.pm

package BB;

print qq{BB required\n};

1;
__END__
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If I change "a b" in AA.pm to something else, which also generates warning (for example "a b c") - everything works as expected - BB.pm successfully required from $SIG{__WARN__} in 1.pl.

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Replies are listed 'Best First'.
Re: Unexpected compiler behavior by Anonymous Monk on Feb 27, 2014 at 01:15 UTC
Does anybody can explain why "require BB;" in 1.pl don't work in this case: the %SIG documentation warns/cautions you against compling perl code (by calling require) from inside the handler ... don't use require (eval) or do(eval) or string eval(eval) inside a signal handler Whatever you're trying to solve, there is probably a better way to solve	[reply]
Re^2: Unexpected compiler behavior by zdm (Beadle) on Feb 28, 2014 at 13:04 UTC
Thanks, now it's clear for me.	[reply]
Re: Unexpected compiler behavior by LanX (Saint) on Feb 27, 2014 at 01:10 UTC
you should be more specific about "what doesn't work" both versions are identical for me and break b/c of compilation errors. some suggestions consider a block eval around require using heavy commands like require within an exception (which can be interrupted again while being executed) is maybe not smartest idea Cheers Rolf ( addicted to the Perl Programming Language)	[reply]