tie stdout with IO::Scalar

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

Have you ever had a problem where you kinda knew what was going wrong ... I have that problem. I am using IO::Scalar and when I tie stdout like so:

    my $str;
     my $io = tie *STDOUT, 'IO::Scalar', \$str;
        print_monks();
    undef $io;
    untie *STDOUT;
       
        # $str now contains the output of the print_monks() function.
[download]

Everything works as expected, as long as the print_monks() function is in the same package. When I use a module that exports a function and then try to capture the output of that function in the same code as above, things go haywire. So this doesn't work:

use Some::Module qw(print_blah);

    my $str;
     my $io = tie *STDOUT, 'IO::Scalar', \$str;
        print_blah();    
    undef $io;
    untie *STDOUT;
        
        # print_blah() prints to stdout.
[download]

How can I get the output into $str in such a case? Thanks.

Comment on tie stdout with IO::Scalar Select or Download Code

Replies are listed 'Best First'.

Re: tie stdout with IO::Scalar
by Mr. Muskrat (Canon) on Jan 27, 2005 at 05:40 UTC

How about you show us an example were it doesn't capture the output? Here's one that shows it working.

#!/usr/bin/perl
use strict;
use IO::Scalar;
use Data::Dump qw(pp);
use Data::Dumper::Simple;

my $str;
my $io = tie *STDERR, 'IO::Scalar', \$str;
pp('monks');
undef $io;
untie *STDERR;

print Dumper($str);

__DATA__
Z:\Perl>ioscalar.pl
$str = '"monks"
';
[download]

[reply]
[d/l]

Re^2: tie stdout with IO::Scalar

by PodMaster (Abbot) on Jan 27, 2005 at 05:52 UTC

system $^X, qw[-le print($_)for(1..22)];

Re: Challenge: Capturing stdout from a function call.

MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
** The third rule of perl club is a statement of fact: pod is sexy.

[reply]
[d/l]

Re^3: tie stdout with IO::Scalar

by jacques (Priest) on Jan 28, 2005 at 03:47 UTC

Thanks for the link.

[reply]

Back to Seekers of Perl Wisdom