If your on 5.8.x, then you should be able to use a "memory file". See perlfunc:open/perlopentut.

open my $memFH, '+>', \my $buffer;
$object->cat( $memFH, $target );
while( <$fh> ) {
    ## do something with it
}

# Or

$buffer =~ s[...][...]mg; #etc
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Thanks for the pointers. A bit of background, since I wasn't terribly clear:

I'm trying to get info out of a Subversion repository, using the Subversion perl bindings. One of those modules has a method (cat) where you specify the a target (including a revision number), and it writes that version of the file to a filehandle you give it. So, there's no file for me to open, but I need to be able to read from the resulting filehandle to get back the file from the repository.

The Memory file seems like a promising tack to take, I'll try that.

Thanks.

BrowserUk's code will let you do that, more or less:

when you run that code, the printed data will be available in $buffer.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

use FileHandle;    

...

$fh = new FileHandle;
$fh->open("> file") or die $!;
$object->cat($fh, $target);
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I'm having a little trouble understanding this.

So presumably doing the simple thing:

open FOO, '>', $filename or die "Can't open $filename: $!\n";
$object->cat(\*FOO, $target);
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Also, you're saying it's OK with STDOUT, but you

want to read the data out of the filehandle

Adding a little more detail will help to get you a more accurate solution.

use strict;
use warnings;

open FH, ">", "test$$.txt" or die $!;

_cat(*FH, "This is a test\n");

sub _cat {
    my $fh = shift;
    my $data  = shift;
    print $fh $data or die $!
}
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use strict;
use warnings;

my $data;

#write to filehandle 
open WH, ">", "test$$.txt" or die $!;
_write(*WH, "This is a test\n");
close WH;

#read from filehandle into $data
open RH, "test$$.txt" or die $!;
_read(*RH, \$data);
close RH;

print $data;

sub _write {
    my $fh = shift;
    my $data  = shift;
    print $fh $data or die $!
}

sub _read {
    my $fh = shift;
    my $data  = shift;
    $$data .= $_ while <$fh>
}
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