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
or state
, which 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 (read: global) variable in the current package, for use within the current lexical scope. In other words, our
has the same scoping rules as my
or state
, 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 the fields
pragma, and attributes are handled using the attributes
pragma, or, starting from Perl 5.8.0, also via the Attribute::Handlers
module. See "Private Variables via my()" in perlsub for details, and fields, attributes, and Attribute::Handlers.