However, if you hand a reference to that variable to another area, or even a reference to a closure that has visibility of the lexical variable, the variable can be tweaked at will.

Note that a subroutine has limited "call-by-reference" semantics as well, if you directly alter @_ rather than copy the values, as is routinely suggested.

And even if you had a copy of a top-level value, if that copy contains references, then the references are pointers into your original data structure. To fully insulate yourself, you must perform a deep copy.

-- Randal L. Schwartz, Perl hacker

Well I'm not playing with references and I'm not passing this variable to anybody else, it is mine and mine alone *muhahahaha*.

I'm starting to worry though that this code isn't being called as I'd expected and is possibly being eval'd into existance or manipulated in some way, because I've been looking more and more into it and it doesn't make sense.

I was hoping that this problem could easily be explained by 'I know too little', but maybe I should be leaning towards 'the guy who wrote this is a code slingin' cowboy'. It isn't the first weird thing I've seen him do *chuckles*

I think we need more information. Merlyn is correct in that a 'my' variable cannot be referenced outside of the block, though a reference passed outside certainly can affect the value.

What I don't understand is how you can know that the value of your variable has changed unless you're doing some execution of code within your block. If you're entering a block with a 'my' variable, leaving that block to execute some other code, and returning to it, the variable is recreated and undefined on the 2nd run. Consider:

sub a {
  my $var = 1;

  &b;                   # Can't touch $var

  eval $set_var_to_2;   # Code in this variable can affect $var

  print "$var\n";
}
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If we could see some code we could explain what's going on, probably. Also make sure you're using 'strict'. This will catch lots of problems like this.

If you're curious, here's what happened with me: At the top of my program, I had

my @data;
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my @stuff, @data;
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Remember, get a minimal test case and if you still have it, post the code and we'll get to work :)

Cheers,
Ovid

On a side note: I always think I've found a problem in Perl, or DBI, or CGI, only to discover that the problem is my code. In a year of doing Perl, I've only encountered one actual bug in Perl. I'll be good money that the issue is your code.

You wouldn't happen to be using mod_perl, would you? If you're using mod_perl, and not BOTH useing strict; and explicitly declaring a package, you can run into wild namespace collisions within a particular Apache child process.

Spud Zeppelin * spud@spudzeppelin.com

I don't think this is a namespace issue. He's talking about problems with the scoping of his variables. It sounds like everything is local to the same namespace (package).