Re: Interpolate variable in a __DATA__ block

Trudge wrote:
>

Hi Trudge.

I'm trying to get a script to interpolate variable values in a
__DATA__ block if possible. This is a kind of alternative to a full-
blown template method. I'm not sure if I can even do what I want,
hence my posting here.

No, you can't do that. But see below.

The following code only goes so far. It correctly prints the value of
$$dataref each time GetData is called, but not in the while loop.
This is where I'm stuck.
>
8<---------------------
#! /usr/bin/perl
use strict;
use warnings;

my @Blocks=qw(first second third);

foreach my $block (@Blocks)
{
GetData($block);
}

sub GetData
{
my $data=shift;
my $dataref=\$data;
print "\$\$dataref is: $$dataref\n";
>
while (<DATA>)
{
chomp;
if ($_ eq "<$data>")
{
next;
print "$_\n";

This print line is unreachable. The next statement before it will
transfer processing back to the beginning of the while loop.

}
if ($_ eq "</$data>")

You should consider using elsif here as the two conditions are mutually
exclusive.

{
last;
}
print "$_\n";

This line will be executed for every line that doesn't look like either
<first> or </first> etc. So, for this data, 'This is the $$dataref
chunk.' will be printed three times. You might want to check out the
range operator, described in perldoc perlop.

Also, $_ here is set as if you had written

$_ = 'This is the $$dataref chunk.';

so no interpolation will take place, and you will get the data line
printed exactly as it is.

}
}


__DATA__
<first>
This is the $$dataref chunk.
</first>
<second>
This is the $$dataref chunk.
</second>
<third>
This is the $$dataref chunk.
</third>

Without knowing what it is you are trying to do it is hard to know how
to help. Do you have reasons for avoiding the 'full-blown template
method'? Or perhaps here-documents would help you? You can learn about
them at

perldoc perlop

Or are you processing XML? There are modules specifically for that
purpose.

HTH,

Rob

.