It looks simple, but I can't find but ugly solutions:

PROBLEM

Assume that $name contains some alphanumeric string, and that I can open the file "$name.pm" (which means that under windows, the file could have been created under a name which differs from $name by upper/lower case letters, since Windows is not case sensitive).

Question: Assuming that if some function I am going to call later, would do a require and import on that file, will it be, or will it not be the case, that a package with the name $name will exists?

EXAMPLE

Say, I have three files:

# This is file Test1.pm
package Test1;
# End of File

# This is file test2.pm
package Test2;
# End of File

# This is file Test3.pm
package Test;
# End of File
[download]

and I go through the files like this:

foreach my $name (qw(Test1 test2 Test3)) {
  unless(file_defines_package_of_same_name($name)) {
    print "$name\n";
  }
}
[download]

I would like to have printed:

test2
Test3
[download]

I would like to have test2 printed, because the package defined in test2.pm is Test2, not test2. I would like to have Test3 printed, because the package defined in Test3.pm is Test, not Test3. The problem is how to write the function file_defines_package_of_same_name.

IDEAS

I have already thought about ways to solve this, but all my solutions seem to be unnecessarily complicated. Here are the two ideas I had so far:

1. Manually open the file and grep for "package $name". Disadvantage: Might give false positive if the line in question appears within a comment or string.

2. Tentatively require the module, then inspect the Perl symbol table for the presence of a $name:: hash:

# NOT TESTED!!!!
sub file_defines_package_of_same_name
{
  my $name=shift;
  eval {  
    require $name;
    { no strict; $name->import(); } # I guess I don't need this, do I?
    defined(eval 'scalar(keys(%'.$name.'::))');
  }
}
[download]

I might get false positives if package $name already existed before, but this is a restriction I can live with. I don't know however about what other nasty consequences this might have to my current package.

RATIONALE

Why do I want to do such a weird test? I am maintaining an application which uses Class::MixinFactory. This module exits Perl if it tries to load a mixin module, and the mixin name (which ends up being a module name) does not match the package name defined in the module.

Hence, a third option for my problem would be to fix Class::MixinFactory, so that instead of exiting, it would throw an exception; but since this is a highly complex module, I would prefer to catch the error before calling MixinFactory, provided there is an easy way to do it.

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