Ave!

stephen showed us recently here how to capture into a scalar variable the output that a Perl subroutine, such as  Pod::Html::pod2html or  Pod::Select::podselect, writes to  STDOUT :

    my $podfile = "some.pod";
    my $scalar = '';
    tie *STDOUT, 'IO::Scalar', \$scalar;
    podselect $podfile;    # reads form $podfile, writes to STDOUT
    untie *STDOUT;
    # now $scalar contains the pod from $podfile
[download]

Now I want to achieve the opposite: feed text from a scalar variable to a subroutine that reads from STDIN.
Is it possible, and how could I do it?

I tried this

    my $scalar = "some pod text";
    tie *STDIN, 'IO::Scalar', \$scalar;
    pod2html;
    untie *STDIN;
    # reads from 'real' STDIN, not from $scalar
[download]

but it does not work as I expected. Am I doing something wrong, or is this a limitation of IO::Scalar?

My script below shows the following:

• tieAngle():   tie *STDIN, 'IO::Scalar', \$text; works as I expected when used with the angle operator  <>
•  pipePod2html(): a workaround - I can print to a pipe, but only if the subroutine is wrapped in an executable script (pod2html.pl or pod2html.bat on Win32)
• tiePod2html():  tie *STDIN, 'IO::Scalar', \$text; does not work with pod2html
• tieOpenDash():  tie *STDIN, 'IO::Scalar', \$text; does not work when I emulate what pod2html does (it opens a file handle to read from STDIN and reads from it).

where 'does not work' means that it does not read from my scalar but from the real STDIN.

My platform is Win2k and perl is 5.6.0, AS build 623.

Rudif

#! perl -w

use strict;
use Pod::Html;
use IO::Scalar;
$|++;

my $text = <<EOT;
=head1 TESTING

First line
Second line
Third line

=cut
EOT

# these work
tieAngle();
pipePod2html();

# these do not work
tiePod2html();
tieOpenDash();


sub tieAngle {   
    print "\n=1 tieAngle================================== OK\n";
    tie *STDIN, 'IO::Scalar', \$text;
    while (<STDIN>) { print "=1=$_"; }
    untie *STDIN;
}

sub pipePod2html {    
    print "\n=pipePod2html================================== OK\n";
    open PIPE, "| pod2html"; # works, because there is a pod2html.bat
    print PIPE $text;
}

sub tiePod2html {    
    print "\n=tiePod2html================================== NOT OK\n";
    tie *STDIN, 'IO::Scalar', \$text;
    pod2html;
    untie *STDIN;
}

sub tieOpenDash {
    print "\n=3 tieOpenDash================================== NOT OK\n
+";
    tie *STDIN, 'IO::Scalar', \$text;
    # similar to what pod2html does:
    open TSCLR, "<-" or die "can't open <-";
    while (<TSCLR>) { print "=3=$_"; }
    close TSCLR;    
    untie *STDIN;
}

__END__
[download]

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