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

In Excel::Template, I'm trying to make some of the warnings I emit only happen if $^W is true. However, in my tests, it's being set to true whether or not I'm setting it in my .t files.

So, I went looking and found that 5.8.5's File::Basename has use warnings; in it. *blinks* Two questions:

  1. I thought that use warnings; in one module won't trigger warnings in that file that module was use'd in. Is that true?
  2. If File::Basename isn't the culprit, how can I find out where $^W is being set to true?

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

Replies are listed 'Best First'.
Re: Who is turning $^W on?
by demerphq (Chancellor) on Nov 08, 2004 at 16:19 UTC 
    $|++;
package Foo;
{

    use strict;
    use warnings;
    use warnings::register;

    sub t {
        warnings::warnif "Bang! '@_'";
        print ": @_\n";
    }
}

package main;
{

    no warnings;
    Foo::t('no warnings');
}
{
    use warnings;
    Foo::t('use warnings');
}
{
    use warnings;
    no warnings 'Foo';
    Foo::t('no warnings "Foo"');
}
{
    no warnings;
    use warnings 'Foo';
    Foo::t('use warnings "Foo"');
}
__END__
: no warnings
Bang! 'use warnings' at C:\Temp\warnings_register.pl line 23
: use warnings
: no warnings "Foo"
Bang! 'use warnings "Foo"' at C:\Temp\warnings_register.pl line 33
: use warnings "Foo"

    [download]
    ---
    demerphq

[reply]
[d/l]
Re: Who is turning $^W on?
by itub (Priest) on Nov 08, 2004 at 15:57 UTC
    Test::Harness calls the tests with the -w option. I think it didn't do that in older versions (well, on further checking it seems like it did).
[reply]
[d/l]
      Gods, that's deep into the Makefile. How do I turn it off, either globally or locally to a given test?

      Being right, does not endow the right to be rude; politeness costs nothing.
      Being unknowing, is not the same as being stupid.
      Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
      Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

[reply]
        While not very pretty, this seems to work when added at the top of the test file: 

        BEGIN { $^W = 0 }

        [download]

        Test::Harness lets you add command-line switches by setting the HARNESS_PERL_SWITCHES environment variable. But that doesn't work for removing the warnings, because it is just added to the existing switches.

[reply]
[d/l]
Re: Who is turning $^W on?
by Aighearach (Initiate) on Nov 08, 2004 at 16:02 UTC
    If you take a look at perldoc perllexwarn you'll find that the warnings pragma is not exactly the same as setting $^W. In particular, the pragma is scoped to the enclosing block. So if $^W is getting set, you can be pretty sure that you need to search for an actual $^W assignment, and not a use warnings pragma.

    You could use the perl debugger to find the offender. Or just grep your files and modules you use for $^W.

    Also note that, if you don't need pre-5.6.0 compatability, then look at perldoc warnings and in particular warnings::register() which provides a good way of turning on and off your own warnings, giving finer control to the user of your module.


    --
    Snazzy tagline here
[reply]

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