Re: calling subroutine inside loop - ERROR - subroutine executes only once

[Discipulus]

hello kaushik9918 and welcome.

Your code is full of strange constructs and even if i'm not a master, i can suggest you some more perlish Perl.

First a slightly modified version of your code:

use strict;
use warnings;

my @corners;
$|++; #get correct order of print and die (STDOUT STDERR)


while(<DATA>){
    $_=~ s/\s+/ / ;
    chop $_;
    push @corners, $_ ;
    print "\n@corners\n";
    }

my $corner;

foreach(@corners){
    $corner=$_;
    &loading_tsc;
    }


sub loading_tsc{
print "DEBUG: loading_tsc received '@_'";
    chdir($corner) or die "\n $!\n";
    print "\n";
    print `pwd`;
    print "\n";
    }
    
__DATA__
AAA
BBB
CCC
DDD

with this code the output is:

AAA

AAA BBB

AAA BBB CCC

AAA BBB CCC DDD
DEBUG: loading_tsc received ''
 No such file or directory

Firstly onother way to get array filled with lines from a file:

    @corners = <DATA> ;

then declare your var within the loop without juggling with $_:

    foreach my $corner(@corners){...

More on when you call your subroutine you pass no argguments to it but you modify a global variable inside it. is not the safer way:

    foreach my $corner(@corners){
               chomp $corner;          # we still need to chomp it..
               &loading_tsc ($corner); # better use of a sub.

    }

Now the chdir-path part: when you deal with path is better have an absolute one to use. In fact assuming you run your original code frome the dir /var/tests you get, as the first item of the array is processed, chdir AAA and if it is succesful you now are in /var/tests/AAA in the next iteration you try to go in /var/tests/AAA/BBB while you probably want /var/tests/BBB.

Better would be to record the starting directory using the core Cwd module and concatenate the path using this base, as in:

use Cwd;
    my $start_dir = getcwd;

...

sub loading_tsc{
    print "DEBUG: loading_tsc received '@_'";
    my $current_corner = shift;
    chdir($start_dir.'/'.$current_corner ) or die "\n $!\n";
    print "\n";
    print `pwd`;
    print "\n";
}

This probably works as you wanted, but is still no safe Perl: when dealing with paths you need to be sure to the right thing possibly for every OS you can encounter. And concatenate paths with '/' can also be annoying. The core File::Spec is handy in this case:

use File::Spec;

..

my $current_dir = File::Spec->rel2abs('.');

..

#in the sub now you can do:

my $path_to_go = File::Spec->catdir( $current_dir , $current_corner );
chdir $path_to_go or die "unable to chdir in $path_to_go\n";

You type some chars more but you can be sure to do the right thing and have a more robust code.

HtH
L*

[kaushik9918]

Thanks