CODEWITHSUNDEEP
perl
user1363308
user1363308

Reputation: 968

What is @ISA array in perl?

our @ISA = "Critter";

In which condition will I use @ISA?

and why our @ISA?.

Upvotes: 16

Views: 23381

Answers (2)

D大雄
D大雄

Reputation: 81

@ISA is stand for ‘is a’， that means the array contains parents' package

Upvotes: 8

Zaid
Zaid

Reputation: 37136

To extend Mat's comment, stuff like this is extensively documented in the perldocs.

Regarding @ISA, here's what it says:

A Class is Simply a Package

...

Each package contains a special array called @ISA . The @ISA array contains a list of that class's parent classes, if any. This array is examined when Perl does method resolution, which we will cover later.

It is possible to manually set @ISA , and you may see this in older Perl code. Much older code also uses the base pragma. For new code, we recommend that you use the parent pragma to declare your parents. This pragma will take care of setting @ISA . It will also load the parent classes and make sure that the package doesn't inherit from itself.

However the parent classes are set, the package's @ISA variable will contain a list of those parents. This is simply a list of scalars, each of which is a string that corresponds to a package name.

our and @ISA go hand in hand because @ISA is expected to be a package variable.

Upvotes: 33

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