in reply to Re^4: Constant subroutine main::C redefined
in thread Constant subroutine main::C redefined

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 }'
$

[download]

Replies are listed 'Best First'.
Re^6: Constant subroutine main::C redefined (diag)
by tye (Sage) on Sep 10, 2012 at 14:04 UTC

    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 }

    [download]

    Or 

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

    [download]

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

    - tye        

[reply]
[d/l]
[select]
Re^6: Constant subroutine main::C redefined
by BrowserUk (Patriarch) on Sep 10, 2012 at 12:38 UTC 

    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

    [download]
    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
[reply]
[d/l]
      Not sure if it helps, but diagnostics shows: 
      Constant subroutine FOO redefined at -e line 1 (#1)
    (S) You redefined a subroutine which had previously been
    eligible for inlining.  See perlsub/"Constant Functions" for
    commentary and workarounds.

      [download]

      Leading to Constant Functions, which mentions a workaround.

[reply]
[d/l]

        Tried that also :( 

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

        [download]

        Dropping the prototype isn't an option either because the constant getting redefined is a very rare occurence (but one that must be catered for), and I don't want to lose the benefits of compile time optimisations for the majority of cases.

        If a constant sub is redefined to be the same value, it doesn't cause the warning:

        C:\test>perl -wE"no warnings 'redefine';sub FOO(){23};sub FOO(){23};sa
+y$];"
5.014002

        [download]

        which will be the majority of cases, but I cannot predict when the edge case might occur so I have to try the redefinition in all cases.

        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
        /div
[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom