Re: Redefining Imported Subs: of scope and no

How do I dynamically redefine imported subroutines?

That's actually quite easy, but say is not being imported; it's not even a subroutine! say is an operator, and use feature 'say'; merely controls whether the compiler recognises it or not. (It always recognises CORE::say, though.)

Some operators can be overridden from within Perl by overriding GLOBAL::CORE::op, and some can't. The following checks whether say can be overridden this way:

>perl -E"say defined(prototype('CORE::say')) ?'yes':'no'"
no
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Its funky syntax doesn't permit it.

say
say LIST
say FILEHANDLE LIST
say BLOCK LIST
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It could be done using a CallChecker, but that involves dropping to C/XS.

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Re^2: Redefining Imported Subs: of scope and no by LanX (Saint) on Feb 11, 2013 at 10:08 UTC
> ... merely controls whether the compiler recognises it or not. (It always recognises CORE::say, though.) Not always, at least for me, with which version did you check? `lanx@nc10-ubuntu:~$ perl -e 'CORE::say("bla")' CORE::say is not a keyword at -e line 1. lanx@nc10-ubuntu:~$ perl -E 'CORE::say("bla")' bla lanx@nc10-ubuntu:~$ perl -version This is perl, v5.10.0 built for i486-linux-gnu-thread-multi` [download] > say is an operator, and use feature `say`; merely ... As a minor nitpick, according to the definitions in perlglossary I'd rather use built-in and not operator to describe `say`, though the differences are indeed fuzzy. Cheers Rolf	[reply] [d/l] [select]
Re^3: Redefining Imported Subs: of scope and no by ikegami (Patriarch) on Feb 11, 2013 at 21:34 UTC
Not always, at least for me, with which version did you check? It apparently went missing until 5.16. As a minor nitpick, according to the definitions in perlglossary I'd rather use built-in and not operator to describe `say`, though the differences are indeed fuzzy. Builtin functions are a slight superset of what both perlop and perlfunc call list operators and named unary operators. `say` is a builtin because `say` is a list operator. (It's fuzzy which builtins aren't operators.)	[reply] [d/l] [select]