Scope - our, my and local

Subroutines in Perl example from a Well House Consultants training course
More on Subroutines in Perl [link]

This example is described in the following article(s):
• Some more advanced Perl examples from a recent course - [link]

Source code: scope Module: P209

# our - default - global
# my - variable is lexically scoped to the block it's declared in
# local - previous global is stored and a new one created that only exists to
# the end of the block it's declared in

# My and local differences -
# local replaces the global variable temporarily so works for special variables such as $"
# local variables are also visible within subs, by my ones are not

sub marine {
        print "The value of \$a_44r is $a_44r\n";
        print "$cherry\n$banana\n";
        }

# Scalar - integer, float, string, reference, regex

# default global, auto typing!
# ----------------------------

$cherry = "Round and Red";
$banana = "Long and Yellow";

$a_44r = 16;
marine;

$a_44r = "The long hard road to Lochinver";
marine;

# With "my" variables is lexically scoped to next }

my $cherry = "Pip wrapped in flesh";
print "$cherry\n";
marine; # Cherry is going to be Round and Red

{
local $banana = "Not really a fruit more a pithstick";
print "$banana\n";
marine; # Banana is going to be the new value
}
marine; # Banana has been restored

=head1

my scopes variable to current block
local takes a backup copy of the variable and restores it at the end of the block

local is BAD and my is GOOD (bit simplistic, mind!)

=cut

__END__

Sample Output

wizard:pl graham$ perl scope
The value of $a_44r is 16
Round and Red
Long and Yellow
The value of $a_44r is The long hard road to Lochinver
Round and Red
Long and Yellow
Pip wrapped in flesh
The value of $a_44r is The long hard road to Lochinver
Round and Red
Long and Yellow
Not really a fruit more a pithstick
The value of $a_44r is The long hard road to Lochinver
Round and Red
Not really a fruit more a pithstick
The value of $a_44r is The long hard road to Lochinver
Round and Red
Long and Yellow
wizard:pl graham$

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