Assign the value to variable in 2 different sub and call the variable based on the value in perl - perl

Question

I need help in calling the value from the variable from 2 different subroutines and assigning the value based on input.
For example: I have 3 different subroutines named sub xxx, sub yyy and sub execute. Two subroutines named as xxx and yyy will be defined as the input of the value. The execute sub will take the input based on the value supplied while executing main.pl:
sub xxx
{
my $input = "repository_1";
}
sub yyy
{
my $input = "repository_2";
}
sub execute
{
$output=$input;
print "This is the Repository connected : $output";
}
When I run the main.pl script, it will call either sub xxx or sub yyy based on the input, and it will execute the output if repository_1 or repository_2.
For example, if I run $main.pl xxx, I am able to connect to sub xxx and skip sub yyy. But I want the sub execute to take the input from sub xxx as repository_1. And so that I can display the $output of the repository like this:
$ main.pl xxx
This is the Repository connected : repository_1

Answer 1

The issue with your code is the my $input lines create variables that are local to the xxx and yyy functions. That means $input will not have any value when you use it in the execute function.
Running your code with use strict and use warnings will show the problem
use strict;
use warnings;
sub xxx
{
my $input = "repository_1";
}
sub yyy
{
my $input = "repository_2";
}
sub execute
{
my $output = $input;
print "This is the Repository connected : $output\n";
}
outputs
Global symbol "$input" requires explicit package name (did you forget to declare "my $input"?) at try.pl line 16.
A very quick fix is to declare $input at a global scope and use #ARGV to trigger the calling of xxx or yyy.
use strict;
use warnings;
my $input;
sub xxx
{
$input = "repository_1";
}
sub yyy
{
$input = "repository_2";
}
sub execute
{
my $output = $input;
print "This is the Repository connected : $output\n";
}
xxx() if $ARGV[0] eq 'xxx';
yyy() if $ARGV[0] eq 'yyy';
execute();
$ perl main.pl xxx
This is the Repository connected : repository_1
NOTE: the use of #ARGV in the code above is purely to create a self-contained script that allows xxx or yyy to be executed on demand. The real code should not only this technique if the control of xxx and yyy needs to be controlled from the command line.
Recommend that all you Perl code includes the use strict and use warnings. It catches issues like this for for you for free.
Without knowing more about your script, it is difficult to make any other recommendations.

Answer 2

A typical use for a dispatch table†, so that we can call the right function based on input (or perhaps other key words but without having to hardcode it)
use warnings;
use strict;
use feature 'say';
my $input = shift // die "Need input\n";
sub xx
{
#say "In xx(), my input: #_";
# ... work out output:
my $output = "repository_1";
return $output;
}
sub yy
{
#say "In yy(), my input: #_";
# ...
my $output = "repository_2";
return $output;
}
sub execute
{
my #output = #_;
print "This is the Repository connected : #output\n";
}
my %dispatch = ( xx => \&xx, yy => \&yy );
# Is there a function to dispatch to for the given input?
my $call_sub = $dispatch{$input} // die "Input ($input) not supported";
execute( $call_sub->() );
Can add more sophisticated handling for unsupported input.
Prints
> perl dispatch_ex.pl yy
This is the Repository connected : repository_2
† In Perl this is normally implemented as a hash which has code references for values and their keys are suitable names that allow us to retrieve them as needed.
A code reference is either a reference to a named function, as used here, or it is an anonymous subroutine
my $code_reference = \&name_of_some_function;
# or
my $code_reference = sub { ... };
This is then a scalar like any other, that can be passed around, stored in arrays or hashes (as a value, as having it as a key -- even though technically allowed -- wouldn't make sense).
Note that it is the function name, no parenthesis. Then it is called (dereferenced) as
$code_reference->( #arguments );
If it is called without any arguments we still need (empty) parenthesis.
Documentation: a tutorial perlreftut and a reference perlref, and perlsub.