our associates a simple name with a package variable in the current
package for use within the current scope. When
use strict 'vars'
our lets you use declared global variables without qualifying
them with package names, within the lexical scope of the
In this way
our differs from
, 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,
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
If more than one value is listed, the list must be placed in parentheses.
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
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
our declaration in the same package, in the same scope, is
our declaration may also have a list of attributes associated
The exact semantics and interface of TYPE and ATTRS are still
evolving. TYPE is currently bound to the use of
and attributes are handled using the
pragma, or starting
from Perl 5.8.0 also via the
"Private Variables via my()" in perlsub for details, and fields,
attributes, and Attribute::Handlers.
The only currently recognized
our() attribute is
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
attribute 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 : unique
also has the effect of
our @x : unique; our %x : unique
. This may be
subject to change.