=over =item our VARLIST X X =item our TYPE VARLIST =item our VARLIST : ATTRS =item our TYPE VARLIST : ATTRS C makes a lexical alias to a package (i.e. global) variable of the same name in the current package for use within the current lexical scope. C has the same scoping rules as C or C, meaning that it is only valid within a lexical scope. Unlike C and C, which both declare new (lexical) variables, C only creates an alias to an existing variable: a package variable of the same name. This means that when C is in effect, C lets you use a package variable without qualifying it with the package name, but only within the lexical scope of the C declaration. This applies immediately--even within the same statement. package Foo; use strict; $Foo::foo = 23; { our $foo; # alias to $Foo::foo print $foo; # prints 23 } print $Foo::foo; # prints 23 print $foo; # ERROR: requires explicit package name This works even if the package variable has not been used before, as package variables spring into existence when first used. package Foo; use strict; our $foo = 23; # just like $Foo::foo = 23 print $Foo::foo; # prints 23 Because the variable becomes legal immediately under C, so long as there is no variable with that name is already in scope, you can then reference the package variable again even within the same statement. package Foo; use strict; my $foo = $foo; # error, undeclared $foo on right-hand side our $foo = $foo; # no errors If more than one variable is listed, the list must be placed in parentheses. our($bar, $baz); An C declaration declares an alias for a package 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 C 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 C declarations. Unlike a second C declaration, which will bind the name to a fresh variable, a second C 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 C 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 C pragma, and attributes are handled using the C pragma, or, starting from Perl 5.8.0, also via the C module. See L for details, and L, L, and L. Note that with a parenthesised list, C can be used as a dummy placeholder, for example to skip assignment of initial values: our ( undef, $min, $hour ) = localtime; C differs from C, which allows use of an unqualified name I within the affected package, but across scopes. =back