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Perl Language Reference Manual
by Larry Wall and others
Paperback (6"x9"), 724 pages
ISBN 9781906966027
RRP £29.95 ($39.95)

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our EXPR

our TYPE EXPR

our EXPR : ATTRS

our TYPE EXPR : ATTRS

our associates a simple name with a package variable in the current package for use within the current scope. When use strict 'vars' is in effect, our lets you use declared global variables without qualifying them with package names, within the lexical scope of the our declaration. In this way our differs from use vars, which is package scoped.

Unlike my, which both allocates storage for a variable and associates a simple name with that storage for use within the current scope, our associates a simple name with a package variable in the current package, for use within the current scope. In other words, our has the same scoping rules as my, but does not necessarily create a variable.

If more than one value is listed, the list must be placed in parentheses.

our $foo;
our($bar, $baz);

An our declaration declares a global variable that will be visible across its entire lexical scope, even across package boundaries. The package in which the variable is entered is determined at the point of the declaration, not at the point of use. This means the following behavior holds:

package Foo;
our $bar;      # declares $Foo::bar for rest of lexical scope
$bar = 20;
package Bar;
print $bar;    # prints 20, as it refers to $Foo::bar

Multiple our declarations with the same name in the same lexical scope are allowed if they are in different packages. If they happen to be in the same package, Perl will emit warnings if you have asked for them, just like multiple my declarations. Unlike a second my declaration, which will bind the name to a fresh variable, a second our declaration in the same package, in the same scope, is merely redundant.

use warnings;
package Foo;
our $bar;      # declares $Foo::bar for rest of lexical scope
$bar = 20;
package Bar;
our $bar = 30; # declares $Bar::bar for rest of lexical scope
print $bar;    # prints 30
our $bar;      # emits warning but has no other effect
print $bar;    # still prints 30

An our declaration may also have a list of attributes associated with it.

The exact semantics and interface of TYPE and ATTRS are still evolving. TYPE is currently bound to the use of fields pragma, and attributes are handled using the attributes pragma, or starting from Perl 5.8.0 also via the Attribute::Handlers module. See 8.1 for details, and "Compile-time class fields" (fields) in the Perl Library Reference Manual (Volume 1), "Get/set subroutine or variable attributes" (attributes) in the Perl Library Reference Manual (Volume 1), and "Simpler definition of attribute handlers" (Attribute::Handlers) in the Perl Library Reference Manual (Volume 2).

ISBN 9781906966027Perl Language Reference ManualSee the print edition