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•Re: Re: •Re: sub and anonymous sub

by merlyn (Sage)
on Jun 20, 2002 at 21:41 UTC ( #176167=note: print w/ replies, xml ) Need Help??


in reply to Re: •Re: sub and anonymous sub
in thread sub and anonymous sub

I was presuming a global variable was already available. If you have use strict, you'd have to "use vars" the variable, yes.

Or, just make it a package variable explictly:

sub my_subroutine { local $main::my_subroutine_level = $main::my_subroutine_level + 1; .... }

-- Randal L. Schwartz, Perl hacker


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Re: •Re: Re: •Re: sub and anonymous sub
by dmmiller2k (Chaplain) on Jun 21, 2002 at 22:02 UTC

    But local also works with lexical variables, doesn't it? IMHO, I didn't think it was necessary for $my_sub_level to be a global, per se. Since perl 5.6 it's been possible to localize nearly any variable; I've localized member variables of class instances, lexicals, arbitrary scalars within complex multi-level structures (hash containing arrayrefs of hashrefs containing hashrefs, etc.).

    Granted, localizing such a thing may (temporarily, subject to the enclosing scope) hide the thing being localized with what is effectively a global, but that's an internal implementation detail that seems to have mattered not, at least with the code in which I've used it.

    To return to the original question, isn't $depth referred to as a closure? Or (perhaps my semantics are incorrect) is sub recurse the closure? Semantics aside, I'm surprised no one mentioned the word.

    dmm

    If you GIVE a man a fish you feed him for a day
    But,
    TEACH him to fish and you feed him for a lifetime
      Since local works with variables in the symbol table and lexical (my) variables have no symbol table entries, you can't use local on a my variable. For example, this fails:
      perl -e 'my $foo; local $foo'
      with the error:
      Can't localize lexical variable $foo at -e line 1.

      -- Mike

      --
      just,my${.02}

        Hmmm, I seem to recall localizing a hash value within a deeply nested structure, like:

        my $root = { some_object => obj }; $root->{some_object} = new Object; my $arrayref = $root->{some_object}->objectMethodReturningEmbeddedArra +yref(); $arrayref->[0] = 5; { local $arrayref->[0] = 0; # execute some code, which sees 0 not 5 } # now array element is 5 again

        I specifically remember wanting to do something like that in 5.004 and not being able to, having instead to do something like this:

        # ... $arrayref->[0] = 5; # ... { my $lcl = $arrayref->[0]; $arrayref->[0] = 0; # execute some code, which sees 0 not 5 $arrayref->[0] = $lcl; } # now array element is 5 again

        dmm

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