Losing __DATA__ when evaling script.

yoda54 has asked for the wisdom of the Perl Monks concerning the following question:

Monks,

I keep getting "readline() on unopened filehandle DATA at (eval 1) line 5." when evaling a script with a __DATA__ section. Would you have any pointers to fix?

Thanks!


#!/usr/bin/perl
use strict;
use warnings;

open(F, "test.pl");
my $f = do { local $/; <F> };
close(F);
eval ($f);


Test.pl:


#!/usr/bin/perl
use strict;
use warnings;

while (<DATA>)
{   
   chomp;
   print "TEST: *$_*\n";
}   

close DATA;


__DATA__
TEST 1 2 3
[download]

Comment on Losing __DATA__ when evaling script. Download Code

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Re: Losing __DATA__ when evaling script. by Loops (Curate) on Jun 19, 2013 at 01:36 UTC
If you add a __DATA__ section to the first script you'll see that it removes the error and allows the second script to be eval'd. Don't think there is a simple way to have an eval block extend the Data section. But for the example you've given above, everything in the first script can be replaced by: `do 'test.pl';` [download]	[reply] [d/l]
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Re: Losing __DATA__ when evaling script. by LanX (Saint) on Jun 19, 2013 at 01:36 UTC
try `do "test.pl"` instead! see docs for "do EXPR" for details! Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]
Re: Losing __DATA__ when evaling script. by tobyink (Canon) on Jun 19, 2013 at 07:35 UTC
The way that the `DATA` file handle works is intimately involved with how Perl loads files via `do`/`require`/`use`. What you are attempting will not work. Load your file using `do`/`require`/`use`; not `eval`. `package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name`	[reply] [d/l] [select]
Re: Losing __DATA__ when evaling script. by tobyink (Canon) on Jun 19, 2013 at 08:45 UTC
For what it's worth, even though I don't think you should be doing this, the following works for your example: `#!/usr/bin/perl use strict; use warnings; { no warnings "once"; open my $fh, "<", "test.pl"; my $code; while (<$fh>) { last if /^__DATA__/; $code .= $_; } local *DATA = $fh; eval $code; }` [download] However, it will break if `test.pl` contains a package statement taking it out of the same package as the wrapper script. `package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name`	[reply] [d/l] [select]