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

I read how do i redirect STDOUT, STDIN, or STDERR to a FILE?, and started to wonder if that can be done lexically scoped.

For some tasks it would be cool to redirect STDOUT to a file or to a scalar (with IO::Scalar), but only in certain scope.

Of course local STDOUT dies with Can't modify constant item in local....

Is there a clean solution?

Update: I just found IO::String and select which works for STDOUT, but is there a way for STDERR as well? I don't need it, I'm just curious ;-)

Perl 6 in German

Replies are listed 'Best First'.
Re: Redirecting STDOUT, lexically scoped
by wind (Priest) on Jul 31, 2007 at 09:43 UTC 
    print "Hello world\n";

{
    local(*STDOUT);
    open(STDOUT, ">some_other_world.txt") or die $!;
    print "Hi other world\n";
    close STDOUT;
}

print "Goodbye world\n";

    [download]
    - Miller
[reply]
[d/l]
[reply]
[d/l]

        Do you understand why? The leading * is there because you're localizing the typeglob. As a result, you'll also effectively localize any $STDOUT, @STDOUT, or %STDOUT you may have defined.

        Not likely to be a problem, but something that bit me at least once as a novice... ;-)

        <–radiant.matrix–>
        Ramblings and references
        The Code that can be seen is not the true Code
        I haven't found a problem yet that can't be solved by a well-placed trebuchet
[reply]
[d/l]
[select]
Re: Redirecting STDOUT, lexically scoped
by FunkyMonk (Bishop) on Jul 31, 2007 at 09:45 UTC
    Use local *STDERR:

    my $out;
print STDERR "before\n";
{
    local *STDERR;
    open STDERR, ">", \$out or die;
    print STDERR "during\n";
}
print "after\n";
print "out: $out\n";

    [download]

    Output:

    before
after
out: during

    [download]

[reply]
[d/l]
[select]

Back to Seekers of Perl Wisdom