Re: How to capture STDOUT/STDERR of a function

STDERR and STDOUT can be localized, like any other global file handle, . That done you can call your function and output will go to the new handle. In perl 5.8,

my ($errors, $output);
sub foo {
    print STDERR "Something to worry about\n";
}

{
    open local(*STDERR), '>', \$errors;
    foo();
}

warn "STDERR ought to be restored now";
$errors =~ s/Something/Nothing/;
print $errors;
[download]

That takes 5.8+ because of the PerlIO trick of opening a file to memory by using a reference to a scalar in the filename slot. In pre-5.8 perls, you can use IO::Scalar or IO::Stringy for the same purpose.

After Compline,
Zaxo

Comment on Re: How to capture STDOUT/STDERR of a function Download Code

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Re^2: How to capture STDOUT/STDERR of a function by Anonymous Monk on Aug 31, 2004 at 18:07 UTC
Thanks, I didn't know about that. What I'm trying to do is to catch the output from Test::Harness, something like the following after your example: `use strict; use Test::Harness; my $out; { open local(*STDOUT),'>',\$out; runtests(); } print $out;` [download] Somehow all results are still printed out to screen, not to the $out variable. I tried STDERR too, the same result. Thanks.	[reply] [d/l]
Re^3: How to capture STDOUT/STDERR of a function by Zaxo (Archbishop) on Aug 31, 2004 at 18:13 UTC
Your use of the idiom is correct. The trouble is that Test::Harness does its own IO remapping. You could try running tests from the command line and redirecting output from there. After Compline, Zaxo	[reply]
Re^3: How to capture STDOUT/STDERR of a function by johnnywang (Priest) on Aug 31, 2004 at 18:09 UTC
Sorry, forgot to login for the above post.	[reply]