How to keep a variable in scope to all subroutines - perl

Question

i am trying to create a module which is like this
package MyModule;
use strict;
use Exporter;
use vars qw($VERSION #ISA #EXPORT #EXPORT_OK %EXPORT_TAGS);
$VERSION = 1.00;
#ISA = qw(Exporter);
#EXPORT = qw(func1);
sub func1 {
my x = shift;
print x;
func2();
}
sub func2 {
print x;
}
and from a perl script, i am calling func1 of the module and passing a variable x. how do i make that variable visible to both subroutines or say all the functions inside that module.
Please help.

Answer 1

Declare $x in the scope of the file using my or our:
my $x;
# subroutines definition
File has the largest lexical scope, so the variable will be visible for the rest of code (unless you re-declare it in some inner scope using my).

Answer 2

Make $x lexical to the package file rather than a single subroutine:
package MyModule;
use strict;
use Exporter;
use vars qw($VERSION #ISA #EXPORT #EXPORT_OK %EXPORT_TAGS);
$VERSION = 1.00;
#ISA = qw(Exporter);
#EXPORT = qw(func1);
my $x;
sub func1 {
$x = shift;
print $x;
func2();
}
sub func2 {
print $x;
}
But this example doesn't really make sense. A more sensible example would be to define a lexical filehandle that multiple subroutines within the package print to:
package PoorManLogger;
my $fileHandle;
sub initialize { open $fileHandle, '<', +shift }
sub alert { print $fileHandle 'ALERT: ', #_, "\n"; }
sub debug { print $fileHandle 'DEBUG: ', #_, "\n"; }
sub close { close $fileHandle; } # Though this isn't technically needed.
1;

Answer 3

One of the main benefits of OO is encapsulation:
#!/usr/bin/perl
package MyModule;
use strict; use warnings;
sub new {
my $class = shift;
bless { x => shift } => $class;
}
sub x {
my $self = shift;
$self->{x} = shift if #_;
return $self->{x};
}
sub func2 {
my $self = shift;
print $self->x, "\n";
}
package main;
use strict; use warnings;
my $m = MyModule->new(5);
$m->func2;
$m->x(7);
$m->func2;

Answer 4

see our
(comments to my suggestion are correct, my suggestion wasn't)