in reply to Re^4: IO::Handle UNIVERSAL::can STDOUT print
in thread IO::Handle UNIVERSAL::can STDOUT print

IO::Handle::can is called with *STDOUT as the first argument just like IO::Handle::print is called with *STDOUT as the first argument. Seeing as *STDOUT isn't an object, can returns false as documented.

It wouldn't hurt for IO::Handle to override can to handle this better, though.

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Re^6: IO::Handle UNIVERSAL::can STDOUT print (suggested change)
by ikegami (Patriarch) on Sep 04, 2009 at 07:03 UTC
    Suggested change: 
    {
    package IO::Handle;

    use strict;
    use warnings;

    use Scalar::Util qw( );

    sub can {
        my $self = shift;
        $self = 'IO::Handle' if !Scalar::Util::blessed($self);
        return $self->SUPER::can(@_);
    }
}

use strict;
use warnings;

$\="\n";

print "\\*STDOUT:    ", \*STDOUT;
print "*STDOUT:     ",  *STDOUT;
print "*STDOUT{IO}: ",  *STDOUT{IO};
print '';

for (1..2) {
    print "\\*STDOUT:    ", (\*STDOUT)  ->can('print') ||0;
    print "*STDOUT:     ",  *STDOUT     ->can('print') ||0;
    print "*STDOUT{IO}: ",  *STDOUT{IO} ->can('print') ||0;
    print '';

    require IO::Handle;
}

    [download]
    \*STDOUT:    GLOB(0x182a044)
*STDOUT:     *main::STDOUT
*STDOUT{IO}: IO::Handle=IO(0x182a054)

\*STDOUT:    0
*STDOUT:     0
*STDOUT{IO}: 0

\*STDOUT:    CODE(0x189cb0c)
*STDOUT:     CODE(0x189cb0c)
*STDOUT{IO}: CODE(0x189cb0c)

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