in reply to Re: Is it possible to create a sub exclusive to a sub?
in thread Is it possible to create a sub exclusive to a sub?

That's just obfuscated syntax for

sub test { $::test{localsub} = sub { print 'localsub1'; return 12345; } unless exists $::test{localsub}; $::test{localsub}->(); }

and implies all the usual ramifications of global variable use.

Makeshifts last the longest.

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Re^3: Is it possible to create a sub exclusive to a sub?
by ihb (Deacon) on Sep 19, 2004 at 10:40 UTC

    *test->{localsub} isn't equivalent to $::test{localsub} in the general case. It just happens to be that in the current package in the code BrowserUk wrote. You probably know that, but I just want to point out that. It's important to realize that *foo doesn't by any means imply the main namespace.

    ihb

    Read argumentation in its context!

      Yes, I know that. I guess I should have added a remark to the effect that I'm not implying that *test->{localsub} is shared across packages. I didn't want to formulate the code using vars or our because that wouldn't have been equivalent — the difference and key point of my argument is that *test->{localsub} is an unchecked use of a global that elides strictures. So I had to use a fully qualified global variable name instead; obviously, the package would have to change according to the context of the code.

      Makeshifts last the longest.

        Which strictures?

        #! perl -slw use strict; sub test{ ## create a 'local' sub the first time we're called ## As many as you like each with it's own name *test->{localsub} = sub{ print 'localsub1'; return 12345; } unless exists *test->{localsub}; ## USE IT WRONG!! *test->{lacolsub}(); *tset->{localhost}(); } print test; __END__ P:\test>test Name "main::tset" used only once: possible typo at P:\test\test.pl lin +e 14. Use of uninitialized value in subroutine entry at P:\test\test.pl line + 13. Can't use string ("") as a subroutine ref while "strict refs" in use a +t P:\test\test.pl line 13.

        Examine what is said, not who speaks.
        "Efficiency is intelligent laziness." -David Dunham
        "Think for yourself!" - Abigail
        "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon
Re^3: Is it possible to create a sub exclusive to a sub?
by BrowserUk (Patriarch) on Sep 19, 2004 at 10:28 UTC

    The only "global variable use", it *main::test, which is in use anyway and has several slots going free. And I guess obfuscated is in the eye of the beholder.


    Examine what is said, not who speaks.
    "Efficiency is intelligent laziness." -David Dunham
    "Think for yourself!" - Abigail
    "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon

      You use %main::test. That that's the same as *main::test{HASH} and *main::test{CODE} happens to be defined doesn't make it any less of a global variable. At least if you're going to go that route, do it directly

      use vars qw( %test ); # ... $test{localsub}->();

      so that strict can catch your typos. (Though it still won't catch $test{lcoalsub}, as opposed to a lexical mistyped as $lcoalsub.) The way you wrote it deprives you of protection wholly.

      Makeshifts last the longest.