Perl 5 version 8.9 documentation
- our EXPR TYPE
- our EXPR : ATTRS
- our TYPE EXPR : ATTRS
ourassociates a simple name with a package variable in the current package for use within the current scope. When
use strict 'vars'is in effect,
ourlets you use declared global variables without qualifying them with package names, within the lexical scope of the
ourdeclaration. In this way
use vars, which is package scoped.
my, which both allocates storage for a variable and associates a simple name with that storage for use within the current scope,
ourassociates a simple name with a package variable in the current package, for use within the current scope. In other words,
ourhas 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.
ourdeclaration 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:
ourdeclarations 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
mydeclarations. Unlike a second
mydeclaration, which will bind the name to a fresh variable, a second
ourdeclaration in the same package, in the same scope, is merely redundant.
ourdeclaration 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
fieldspragma, and attributes are handled using the
attributespragma, or starting from Perl 5.8.0 also via the
Attribute::Handlersmodule. See Private Variables via my() in perlsub for details, and fields, attributes, and Attribute::Handlers.
The only currently recognized
uniquewhich indicates that a single copy of the global is to be used by all interpreters should the program happen to be running in a multi-interpreter environment. (The default behaviour would be for each interpreter to have its own copy of the global.) Examples:
Note that this attribute also has the effect of making the global readonly when the first new interpreter is cloned (for example, when the first new thread is created).
Multi-interpreter environments can come to being either through the fork() emulation on Windows platforms, or by embedding perl in a multi-threaded application. The
uniqueattribute does nothing in all other environments.
Warning: the current implementation of this attribute operates on the typeglob associated with the variable; this means that
our $x : uniquealso has the effect of
our @x : unique; our %x : unique. This may be subject to change.