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Scope - our, my and local
Subroutines in Perl example from a Well House Consultants training course
More on Subroutines in Perl [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 $a_44r is The long hard road to Lochinver Round and Red Long and Yellow wizard:pl graham$ Learn about this subject
This module and example are covered on the following public courses:
* Perl Programming * Perl bootcamp * Learning to program in Perl * Perl Programming Also available on on site courses for larger groups Books covering this topic
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