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How do I use @ISA and use strict at the same time?
( #85738=categorized question: print w/ replies, xml ) Need Help??
Contributed by thoglette on Jun 05, 2001 at 12:45 UTC
Q&A  > object-oriented programming


Description:

By default (5.004_02) adding
use strict;
causes the usual inheritance line of
@ISA = ("InheritedClass");
to fail for not being fully declared.
Trying local and my don't work - when running Perl complains Can't locate object method "new" via package

Answer: How do I use @ISA and use strict at the same time?
contributed by davorg

use vars qw(@ISA);

Answer: How do I use @ISA and use strict at the same time?
contributed by Vynce

TIMTOWTDI: 

use strict;
package Question::Loaded;
use vars ('@ISA');
@ISA = ('Question');

[download]
or 
package Question::Open;
@ISA = ('Question');

use strict;

[download]
or 
package Question::MillionDollar;
use strict;
our @ISA = ('Question'); # if (perl -v >= 5.6) 

[download]
and there are other ways, too. it's a matter of style.

Edit by tye: Note that use strict can appear before the package line but that putting use vars before the package line will cause the file to fail to compile while putting our before the package line will not work in less obvious ways.

Answer: How do I use @ISA and use strict at the same time?
contributed by merlyn

If the parent class is in a separate file, consider using base.

Answer: How do I use @ISA and use strict at the same time?
contributed by Anonymous Monk

I think the best is 

package Question;
@Question::ISA=("Another");

[download]
Answer: How do I use @ISA and use strict at the same time?
contributed by Narveson 

use strict;
package Wombat;
use base 'Marsupial';

[download]
See Conway, Perl Best Practices, chapter 16: Class Hierarchies, Inheritance.

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