in reply to Re^7: Constant subroutine main::C redefined
in thread Constant subroutine main::C redefined

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

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Re^9: Constant subroutine main::C redefined
by tinita (Parson) on Sep 10, 2012 at 13:50 UTC
    so what about delete $main::{C}? did you try?
[reply]
[d/l]

      It works in main, but the target won't always be main. Still trying to get the syntax right for an arbitrary package.

      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
      /divp align=right
[reply]
        no strict "refs";
my $p = "main";
delete ${ $p."::" }{C};

        [download]
[reply]
[d/l]
        String eval for sub definition might be helpful here, though I don't know if that messes with the optimization. Minus that, 
        sub FOO(){23}; 
BEGIN{eval sprintf 'delete $%s::{FOO}', __PACKAGE__}
sub FOO(){42};

        [download]
        might hit your need.

        #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

[reply]
[d/l]
Re^9: Constant subroutine main::C redefined
by tobyink (Canon) on Sep 10, 2012 at 21:47 UTC

    You need the if $] in the first definition of FOO. That should prevent it being constant-folded.

    perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'
[reply]
[d/l]
      That should prevent it being constant-folded.

      It would. Which is why I cannot use that solution.

      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]

        Well, if you want constant folding, then you'll have to deal with the warning being generated. It's a mandatory warning.

        Of course, just because the warning will be generated; doesn't mean it has to be displayed. $SIG{__WARN__} can catch and hide it.

        perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'
[reply]
[d/l]

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