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Re^3: Constant subroutine main::C redefined

by tinita (Parson)
on Sep 10, 2012 at 12:08 UTC ( #992739=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Constant subroutine main::C redefined
in thread Constant subroutine main::C redefined

like I said, it doesn't work from outside. for constants the redefinition happens in constant.pm.
you could delete $main::{C}


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Re^4: Constant subroutine main::C redefined
by Corion (Pope) on Sep 10, 2012 at 12:11 UTC

    Also note that "redefining" a constant does not necessarily do what BrowserUk wants. The constants get inlined, so redefining them only works from that point on:

    use constant C => 1; sub c { C }; use constant C => 2; sub d { C }; print c(); # 1 print d(); # 2
Re^4: Constant subroutine main::C redefined
by BrowserUk (Pope) on Sep 10, 2012 at 12:16 UTC
    like I said, it doesn't work from outside. for constants the redefinition happens in constant.pm.

    I'm not using the constant pragma.


    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

    RIP Neil Armstrong

      care to show some code and inform us which perl version you are using? *sigh*
      talking about constants without further explanation for me means using constant.pm. everything else is just a subroutine with an empty prototype.
      talking about a subroutine with an empty prototype?
      $ perl5.16.0 -wE' no warnings "redefine"; sub FOO () { 23 } sub FOO () { 42 }' $

        C:\test>perl -wE"no warnings 'redefine';sub FOO(){23};sub FOO(){42};sa +y $];" Constant subroutine FOO redefined at -e line 1. 5.014002

        With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.

        RIP Neil Armstrong

        perldiag says "(S) A severe warning (enabled by default)." which is probably part of the problem. But it is still easy to get around in a couple of different ways:

        #!/usr/bin/perl -w BEGIN { $SIG{__WARN__} = sub { warn @_ if $_[0] !~ /^Constant subroutine/; } } sub FOO() { 23 } sub FOO() { 42 }

        Or

        #!/usr/bin/perl -w sub FOO() { 23 } BEGIN { no warnings 'misc'; undef &FOO if ! @ARGV } sub FOO() { 42 }

        I threw in the 'if ! @ARGV' just so one can see the warning produced or suppressed by the same code.

        - tye        

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