zenmaster wrote:

But they often can achieve the same result.
And usually people use them without even noticing the difference...

Well, let's look at a few other things that people use "without even noticing the difference":

• chop and chomp.

  They're pretty darned close, until you discover the last line of the file you read from doesn't have a newline.

• &somesub and somesub().

  Usually you won't notice a difference, but the first one makes the sub call and passes the current value of @_ as the arguments. Hmm... if you make such a sub call from within another sub and are expecting no arguments to be passed...

• $somearray[0] and @somearray[0].

  This one bites quite a few programmers. It usually doesn't cause a problem, but guess what happens when you do something like @vals[3] = somesub() and &somesub uses wantarray? Then you've got trouble and it can be a nasty bug to find.

• my and local.

  My creates a lexical variable that's private to a package (note that this is NOT a package variable). local temporarily replaces the current package variable with another value.

Run the following code:

use strict;
use warnings;

print test();

sub test {
    local $x;
    $x = 17;
}
[download]

Guess what? That generates an error similar to the following:

Global symbol "$x" requires explicit package name at C:\WINNT\Profiles
+\Ovid\Desktop\test.pl line 7
[download]

That's because local does not create variables. Replace the local with a my and it works fine.

For more information, see Coping with Scoping and Seven Useful Uses of local. Both, oddly enough, were written by Dominus, the monk you chose to take to task.

Cheers,
Ovid

Update: After chatting with zenmaster and reading his update, I see that this mostly appears to be a misunderstanding of what he meant to say, but I'll leave the post as it's useful information.

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