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Re: Problem to inspect scalars in STASH

by educated_foo (Vicar)
on Feb 15, 2012 at 05:08 UTC ( #953834=note: print w/replies, xml ) Need Help??

in reply to Problem to inspect scalars in STASH

Yes, this is annoying, and even more so when defined(@array) and defined(%hash) become deprecated. The solution I came up with is to use defined($$name) for scalars, and defined(*{$name}{THING}) for the others. I think it works on all current Perls without polluting the stash, e.g.
main @> $Test::x = 1; @Test::y = qw(2 3); %Test::z = (a => 'b'); main @> keys %Test:: y x z main @> join ' ', "SCALARS:", grep defined(${"Test::$_"}), keys %Test: +: 'SCALARS: x' main @> join ' ', "ARRAYS:", grep defined(*{"Test::$_"}{ARRAY}), keys +%Test:: 'ARRAYS: y' main @> join ' ', "HASHES:", grep defined(*{"Test::$_"}{HASH}), keys % +Test:: 'HASHES: z' main @> join ' ', "SCALARS:", grep defined(${"Test::$_"}), keys %Test: +: 'SCALARS: x'

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Re^2: Problem to inspect scalars in STASH
by LanX (Bishop) on Feb 15, 2012 at 16:05 UTC
    Thanks for your help... :)

    > The solution I came up with is to use defined($$name) for scalars,

    Sorry, that's not a solution because it excludes all declared package variables which became undef in the meantime.

    Think of something like  $flag = () in the middle of the code. I'm trying to fix the tab-expansion in the perldebugger, actually $f#TAB# lists all symbols starting with f, no matter which slot is used.

    DB<223> sub flo {} => 0 DB<224> $f # type TAB $f $find $flag $flo

    As a workaround I could include all symbols where only the scalar slot is defined, but if someone decides to have equally named sub &flo AND scalar $flo where the latter is undef, I can't tell if the scalar belongs to the code or not.

    While this cases seems rare enough - most people tend to use different names for different sigils - it's not a 100% solution.

    If there is no better suggestion, I will need to parse the code to reliably find all scalars.

    >Yes, this is annoying,

    FWIW I consider this behavior a bug.

    Cheers Rolf

      You're right, of course, and I agree that the SCALAR auto-vivification thing is a bug. I remember discussing this with some P5P folks awhile back, and IIRC this auto-creation of the SCALAR slot was fairly well-baked into the core. Still, you think that wandering through the symbol table should be easy -- it's just a hash of GLOBs, right? -- and then you run into all this stuff. *sigh*

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