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Re: Why " subroutined redefined" warning comes?

by joeface (Pilgrim)
on Nov 04, 2006 at 19:10 UTC ( #582263=note: print w/ replies, xml ) Need Help??


in reply to Why " subroutined redefined" warning comes?

Admittedly, I'm not the sharpest tool in the shed when it comes to packages, modules, namespaces, and OO-related Perl stuff, but I worked around the same warning earlier today.

I have a module called "Spinner.pm", that contains a subroutine called "spin()". I created another sub in the main script called "spin()". So, Perl didn't seem to know whether to use the sub in Main::, or the sub in Spinner.pm.

The script that threw the error:

use Spinner.pm; for (1 .. 1000) { spin(); } sub spin { print "i am the second spin() sub\n"; }

I got the warning: "Subroutine spin redefined at script.pl line 21". Perl then went ahead and used the spin() sub that was in the main script.

I got around this by doing the following:

use Spinner.pm; for (1 .. 1000) { spin(); spin2::spin(); } package spin2; sub spin { print "i am the second spin() sub\n"; }

By explicitly specifying package::subroutine(), Perl knew which one to use. I got the functionality of both calls, with no warnings.

So, although I agree with davido, and would advise against giving a sub the same name as one that already exists in one of your loaded modules (or in your main script), if you have to do it, you have to put the "duplicate" sub in a different package. Note that I have no idea how this would affect your variable scoping, or whatever else is going on in your script.


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Re^2: Why " subroutined redefined" warning comes?
by jdtoronto (Prior) on Nov 04, 2006 at 19:52 UTC
    Obviously Spinner.pm is exporting the function into the MAIN namespace. Stop it exporting, then you can do:
    use Spinner.pm; for (1 .. 1000) { Spinner::spin(); } sub spin { print "i am the second spin() sub\n"; }
    and you don't have a duplicate. Depending on the internals of Spinner, you may be able to do:
    use Spinner();
    to stop it importing into the MAIN namespace.

    jdtoronto

      Ahhhh... learned something new, thanks to your reply.

      So, yes, I want Spinner to export the spin() function, to save me from having to do Spinner::spin(), but now I know why I have it that way, and what to change if I decide not to export it.

      You've also shown us a different way to keep the subs separate, if need be.

      Thanks!

        An option if you don't import it is to alias it to another name in your package.

        use Spinner (); local *s_pin = \&Spinner::spin; s_pin(); spin();

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