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String Buffer

by kayos (Sexton)
on Apr 25, 2000 at 21:12 UTC ( #9037=sourcecode: print w/replies, xml ) Need Help??
Category: strings
Author/Contact Info T.R. Fullhart,

Sometimes I encounter a script or program that wants to print directly to STDOUT (like Parse::ePerl), but I want it in a scalar variable. In those cases, I use this StringBuffer module to make a filehandle that is tied to a scalar.


use StringBuffer; my $stdout = tie(*STDOUT,'StringBuffer'); print STDOUT 'this will magically get put in $stdout'; undef($stdout); untie(*STDOUT);
# $Id:,v 1.1 2000/04/03 22:53:04 kayos Exp $
package StringBuffer;

    my ($class, $c) = @_;
    return bless(\$c,$class);

sub PRINT {
    my ($self) = shift;
    ${$self} .= join('', @_);

sub PRINTF {
    my ($self) = shift;
    my ($fmt) = shift;
    ${$self} .= sprintf($fmt, @_);

#   sometimes Perl wants it...
sub DESTROY { };

Replies are listed 'Best First'.
Re: String Buffer
by bruno (Friar) on Aug 24, 2008 at 13:58 UTC
    Thanks a lot, I can make real use of this!
      Or, without using tie:
      open my $oldout, ">&STDOUT" or die "Can't dup STDOUT: $!"; my $stdout; close STDOUT; open STDOUT, ">", \$stdout or die $!; # This is where the magic happen +s print "foo\n"; close STDOUT; open STDOUT, ">&", $oldout or die $!; print "Done fooling around\n"; print $stdout; # foo

      This is mostly copy & pasted from open, so you might want to look there for more.

      Unless I state otherwise, all my code runs with strict and warnings

        In fact, that uses a perlio layer silently.

        I've been wishing a perlio layer that allows you to simply open a stream that behaives like any tied handle eg.

        use StringBuffer; use PerlIO::Tied; # Note: never close one of the three standard handles. It's almost alw +ays a bad idea. open OLDSTDOUT, ">&=STDOUT"; open STDOUT, ">:tied(StringBuffer)"; # I presume extra arguments to ti +e get passed as extra argument to open print STDOUT "this magically gets put to \$stdout\n"; open STDOUT, ">&=OLDSTDOUT"; print STDOUT "this gets put to the original standard output again\n";

        This gets even more useful if you want to use a tied io handle from the command line eg. perl -MPerlIO::Tied -we 'some code' ':tied(SomeModule, arguments)'.

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