Using File Handle in hash

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

If I stick a file handle into a hash, is there a way to read from the filehandle ala <$handle> without copying the file handle to a scalar first? Here's some code...

#! /usr/bin/perl -w -T

use strict;

# assuming 'foo' exists
open( my $handle, '<', 'foo' );
my %hash = ( handle => $handle);

# prints out GLOB(0x9d2cc28)
while( <$hash{handle}> ) {
    print;
}
my %worse_yet = ( hash => \%hash );

# won't compile
while( <$worse_yet{hash}->{handle}> ) {
    print;
}
# I tried *{$worse_yet{hash}->{handle}} and it didn't work either
[download]

Comment on Using File Handle in hash Select or Download Code

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Re: Using File Handle in hash by ikegami (Patriarch) on Jun 30, 2009 at 20:49 UTC
That usage of `<>` is a shorthand for `readline`. If you switch to `readline` it still adds to the `defined` check and the assignment to `$_`. `$ perl -MO=Deparse -e'while (<$fh>) {}' while (defined($_ = <$fh>)) { (); } -e syntax OK $ perl -MO=Deparse -e'while (readline($fh)) {}' while (defined($_ = <$fh>)) { (); } -e syntax OK` [download]	[reply] [d/l] [select]
Re: Using File Handle in hash by Fletch (Bishop) on Jun 30, 2009 at 20:17 UTC
Quoth the docs for print: Note that if you're storing FILEHANDLEs in an array, or if you're using any other expression more complex than a scalar variable to retrieve it, you will have to use a block returning the filehandle value instead: `print { $files[$i] } "stuff\n"; print { $OK ? STDOUT : STDERR } "stuff\n";` [download] Update: Duur, read not write. You want readline (`readline( $hash{handle} )`). Ignore that first part. The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l] [select]