Re: Tricky scope problem

I have a global variable going out of scope

Global variables don't go out of scope. That's because they are global. In the code you've posted there's no global variable at all. There's a $gVar which is lexically scoped via my on file level.

Do you mean, $gVar doesn't hold the last hashref from $listOfHashRef after calling Foo() ? That's because the $gVar as a foreach iterator aliases (masks) the outer $gVar. Consider:

use strict;

sub generateList {
    my $ref;
    push @$ref, { funPtr => do { my $x = $_; sub { print "in $x\n" } }
+ }
        for qw(foo bar);
    $ref;
}

my $gVar;

sub Foo
{

   my $listOfHashRef = generateList();
   my $functionPtr;

   foreach (@$listOfHashRef) {
       $gVar = $_;
       $functionPtr = $gVar->{funPtr};
       # Assert:  $gVar has all of its values here
       $functionPtr->();
   }
}

# Assert:  The $gVar->{funPtr} does indeed point to Bar
sub Bar
{
    print "$gVar\n";
    # Assert:  $gVar is null
}
Foo();
Bar();
__END__
in foo
in bar
HASH(0x88a1660)
[download]

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Re^2: Tricky scope problem by Anonymous Monk on Apr 13, 2009 at 14:41 UTC
Thank you mighty perl Monks for your wisdom! (this is the orginal poster, I'll have to make a user name at some point). I do appologize for the confusion on debugging, all of your assumptions were correct and and the forloop was masking my outer variable. I was attempting to showcase the problem from a much larger program, after seeing your code snippits, I think I have a better idea of how to showcase things (I will read the linked page too, though I do point out, I knew what I meant, and you knew what I meant too, beginers luck?). I have read many web pages on perl scoping (global vs lexical) including the documentation on key words 'my' and 'our' packaged within the perl install. I'm afraid I still think of "my $var;" used out side of a function as global to the file which would be its C/C++ equivalent and it appears to be the case in perl (excepting its use in forloops). I tend to think of using "our $var;" as the equivalent of an external command in C/C++, a way to link a file global var across mulitple files. Is this incorrect? How does one declare a global variable if "use strict;" is in effect? As soon as I declare it via 'my', it is lexical not global.	[reply]
Re^3: Tricky scope problem by shmem (Chancellor) on Apr 13, 2009 at 19:52 UTC
I tend to think of using "our $var;" as the equivalent of an external command in C/C++, a way to link a file global var across mulitple files. This is correct; but in all files this variable should be declared with our. But there's more to variables declared with 'our': declaring a variable with 'our' creates a package global in the package in which it is declared the short name of this variable is visible throughout its lexical scope, even spanning packages Example: `package Foo; our $foo = 'foo'; # $Foo::foo now exists package main; print $foo,"\n"; # $Foo::foo, not $main::foo ! print $Foo::foo,"\n"; __END__ foo foo` [download]	[reply] [d/l]