How to tell if subroutine param is filehandle

[mcdavis941@netscape.net]

Hi,

Is there a way for a subroutine to tell when it got passed a FILEHANDLE?

Running a quick test suggests a way, which is to check the first char of the result of interpolating the subroutine param as a string. Can anyone say whether this is robust and if not what might be a better approach? Thank you.

testprintorstring.pl:
---------------------

use warnings;
use strict;

{
my $string = "xyz";
testprint( "Filehandle", *STDIN );
testprint( "Stringref", \$string );
}

sub testprint {
my( $descr, $r_data ) = @_;
print "$descr: $r_data ", ref($r_data), "\n";
}

output:
-------

D:\MCD\dvl\scripts>perl testprintorstring.pl
Filehandle: *main::STDIN
Stringref: SCALAR(0x155a898) SCALAR




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[Jeff 'Japhy' Pinyan]

On Feb 1, [email]mcdavis941@netscape.net[/email] said:

>Is there a way for a subroutine to tell when it got passed a FILEHANDLE?

You could test to see if its ref() returns "GLOB" or "IO::File" or
"IO::Handle", etc., but I think it's a nifty idea to do:

if (defined fileno($arg)) {
# it's an open filehandle
}

--
Jeff "japhy" Pinyan [email]japhy@pobox.com[/email] [url]http://www.pobox.com/~japhy/[/url]
RPI Acacia brother #734 [url]http://www.perlmonks.org/[/url] [url]http://www.cpan.org/[/url]
<stu> what does y/// stand for? <tenderpuss> why, yansliterate of course.
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