Where to declare?

[Rich36]

Part of the piece of code I'm working on involves getting a list of valid directories from the user. The problem that I'm having is this...
The code below works, but I get a error message stating.

Variable "@dirlist" will not stay shared at test.pl line 17.
Variable "@dirlist" will not stay shared at test.pl line 24.

Where/how do I declare that variable to avoid that warning? If I place the "my @dirlist" within the "getAns()" sub, it redeclares the variable and erases any information that was added. If I leave it out of that sub, I get that warning.

#!/usr/bin/perl -w

use strict;

my @dirs = &getDirs();

sub getDirs() {

    my @dirlist; # PROBLEM!!!
    sub getAns() {
        print qq(Enter a valid directory: );
        chomp(my $ans = <STDIN>);
        if ($ans ne "") {
            if ($ans =~ m/foo/g) {
                push(@dirlist, $ans);
                &getAns;
            } else {
                print qq(That is not a valid directory!\n);
                &getAns;
                }
            } else {
                return @dirlist;
            }
        }
    }

    my @dirs = &getAns();
    
    if (@dirs) {
        return @dirs;
    } else {
        die qq(No directories have been entered!\n);
    }

}

Thanks in advance for the help,
Rich36

[Masem]

Not the specific answer to your problem, but do you really need a nested sub for this application? A while loop is much much easier to build around than this. KISS. eg:

my @dirlist;
print qq(Enter a valid directory);
chomp (my $ans = <STDIN>);
while ( $ans ne "" ) {
   if ( $ans =~ m/foo/g ) {
       push @dirlist, $ans;
   } else { 
       print qq(That is not a valid dir);
   }
   print qq(Enter a valid directory);
   chomp ($ans = <STDIN>);
}
# @dirlist is now filled happily

-----------------------------------------------------
Dr. Michael K. Neylon - [e-mail] || "You've left the lens cap of your mind on again, Pinky" - The Brain
"I can see my house from here!"
It's not what you know, but knowing how to find it if you don't know that's important

[traveler]

As an aside to your suggestion, I remember a programming course that taught recursion before loops and then taught while loops as an alternative to the "more natural" tail recursion. Interesting what some consider "simple".

--traveler

[blackmateria]

Move the declaration of @dirlist after the nested sub (getAns), then pass it in as a hard reference:

sub getDirs() {

    sub getAns() {
        my ($dirlist) = @_; # new
        print qq(Enter a valid directory: );
        chomp(my $ans = <STDIN>);
        if ($ans ne "") {
            if ($ans =~ m/foo/g) {
                push(@$dirlist, $ans); # note the @$dirlist
                &getAns;
            } else {
                print qq(That is not a valid directory!\n);
                &getAns;
                }
            } else {
                return @$dirlist; # note the @$dirlist
            }
        }

    my @dirlist;
    my @dirs = getAns(\@dirlist); # note the \@dirlist
    
    if (@dirs) {
        return @dirs;
    } else {
        die qq(No directories have been entered!\n);
    }

}

For more information on hard references, take a look at perlref.

Just a stylistic note, you don't need to put the & on getAns to call if if you're already using () (the original has a line which read my @dirs = &getAns()). As a matter of fact, you should stay away from using & to call subroutines unless you understand how it's different from calling them with (). Calling with & makes @_ in the called subroutine an alias for @_ in the caller; () makes a copy instead. So changing the parameters in the subroutine could affect the variables used in the main program. This is probably not what you expect! Be careful. If I were you, I'd change the places in your code that call &getAns to getAns().

Anyway, hope this helps.

[Rich36]

Thanks very much for your help. The "while" loop definitely simplified things.

And this -
As a matter of fact, you should stay away from using & to call subroutines unless you understand how it's different from calling them with (). Calling with & makes @_ in the called subroutine an alias for @_ in the caller; () makes a copy instead. So changing the parameters in the subroutine could affect the variables used in the main program. This is probably not what you expect! Be careful.
- is definitely information I can use. I tend to be pretty liberal about using both "&" and "()" in my subroutine calls. I didn't realize there was a difference.

Thanks for the help and enlightenment...
Rich36

[tye]

Actually, that bit of text you quoted is incorrect. Using & without () does what is described. Using both together is probably a good practice, especially if you aren't in the habit of giving your subroutines names with mixed case. See (tye)Re: A question of style for more info.

        - tye (but my friends call me "Tye")