Using @ISA and strict

chris Blog
0

Ok,

In Perl we use the following code to make a sub class of a class.

@ISA = (inherited class);

However if you are using strict like below,

package MySubClass;
use strict;
@ISA = qw( MyClass );
...

you will get the error Global symbol “@ISA” requires explicit package name (did you forget to declare “my @ISA”?)

Using My @ISA like below will just give you the error Can’t locate object method “MyMethod” via package “MySubClass” because you just made it local.

package MySubClass;
use strict;
my @ISA = qw( MyClass );
...

So how can I fix this? Well there are many different options, I have listed some of them here.

The first one is simple, just place the use strict after the @ISA

package MySubClass;
@ISA = qw( MyClass );
use strict;
...

Another option is to use the vars declaration.

package MySubClass;
use strict;
use vars ('@ISA');
@ISA = qw( MyClass );
...

This one is probably the most correct way and that is to declare the @ISA with our. However I believe this will only work with perl greater than 5.6 so you may want to add use 5.6.0;

package MySubClass;
use strict;
use 5.6.0;
our @ISA = qw( MyClass );
...

So there you go, some fine examples on how to use @ISA and strict.

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