require only parses a file if it hasn't already been required before. The first time vars.pl is required occurs in foo.pm in the package "foo" and so $bar= "I AM BAR." actually sets $foo::bar= "I AM BAR.". The second time vars.pl is required, Perl says, "Yes, you require that file and I've already loaded it so I don't need to do anything here". So $main::bar is never set.

If you want to set a variable in the caller's package every time your file is required, then I suggest you make the file a real module, like: 

package MyVars;
use base qw(Exporter);
use vars qw(@EXPORT_OK $bar);
@EXPORT_OK= qw($bar);
$bar="I AM BAR.";
1;

[download]

Then you use it via use MyVars qw($bar);.

You can also include files via "do" to have them parsed every time, but I strongly frown on that.

        - tye (but my friends call me "Tye")

In reply to RE: require in .pm and .pl = blow up? by tye
in thread require in .pm and .pl = blow up? by Anonymous Monk

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