Re: I need a simple explantion of the difference between my() and local()

[mothra]

From perldoc perlfaq7:

What's the difference between dynamic and lexical (static) scoping? Between local() and my()?

local($x) saves away the old value of the global variable $x, and assigns a new value for the duration of the subroutine, which is visible in other functions called from that subroutine.

...

my($x) creates a new variable that is only visible in the current subroutine.

[$code or die]

if you use my() inside an if .. else conditional, it is also only visible in that scope.

There is quite thorough documentation in perlman:perlsub

$code or die
$ perldoc perldoc

[merlyn]

if you use my() inside an if .. else conditional, it is also only visible in that scope.

I think that's just a special case of what Dominus said at Re: I need a simple explantion of the difference between my() and local():

The variable is only available inside the block in which you declared it.

Or were you implying something extra special there?

-- Randal L. Schwartz, Perl hacker

[buckaduck]

Update: I added an example for an if() conditional, which was the original poster's actual intent.

I think that his implication was just a clarification of a subtlety that escapes many Perl novices.

The point is that you don't have to use the my() declaration between curly braces to define its scope within a block of code. You can use my() within the condition of an if/else block:

if ( (my $name = GetName()) =~ /^\w+$/) ) {
  print $name;
}

And the variable $name has the scope of that conditional.

You can also use the my() declaration in a loop control statement:

while (my $line = <>) {
  print $line;
}

foreach my $name (@people) {
  print $name;
}

And the variable's scope is that of the loop. It was certainly a revelation for me, once upon a time...

buckaduck

[$code or die]

It seems I have err'd

I replied to Dominus instead of mothra - which was my original intent - mothra was talking about lexical variables in subroutines. I wanted to point out that it applies to conditional blocks as well.

$ perldoc perldoc

Update: Nope - unless I am 'very' short-sighted - I think I did reply to mothra.