Declares the BLOCK or the rest of the compilation unit as being in the
given namespace. The scope of the package declaration is either the
supplied code BLOCK or, in the absence of a BLOCK, from the declaration
itself through the end of current scope (the enclosing block, file, or
eval). That is, the forms without a BLOCK are operative through the end
of the current scope, just like the my, state, and our operators.
All unqualified dynamic identifiers in this scope will be in the given
namespace, except where overridden by another package declaration or
when they're one of the special identifiers that qualify into main::
,
like STDOUT
, ARGV
, ENV
, and the punctuation variables.
A package statement affects dynamic variables only, including those
you've used local on, but not lexically-scoped variables, which are created
with my, state, or our. Typically it would be the first
declaration in a file included by require or use. You can switch into a
package in more than one place, since this only determines which default
symbol table the compiler uses for the rest of that block. You can refer to
identifiers in other packages than the current one by prefixing the identifier
with the package name and a double colon, as in $SomePack::var
or ThatPack::INPUT_HANDLE
. If package name is omitted, the main
package as assumed. That is, $::sail
is equivalent to
$main::sail
(as well as to $main'sail
, still seen in ancient
code, mostly from Perl 4).
If VERSION is provided, package sets the $VERSION
variable in the given
namespace to a version object with the VERSION provided. VERSION must be a
"strict" style version number as defined by the version module: a positive
decimal number (integer or decimal-fraction) without exponentiation or else a
dotted-decimal v-string with a leading 'v' character and at least three
components. You should set $VERSION
only once per package.
See Packages in perlmod for more information about packages, modules, and classes. See perlsub for other scoping issues.