Exporter (Perl in a Nutshell, 2nd Edition)

8.66. Exporter

Implements a default import method for other modules to inherit if they don't want to define their own. If you are writing a module, you can do the following:

package Module;
use Exporter ( );
@ISA = qw(Exporter);

@EXPORT = qw(...);              
@EXPORT_OK = qw(...);           
%EXPORT_TAGS = (tag => [...]);

in which @EXPORT is a list of symbols to export by default, @EXPORT_OK is a list of symbols to export on request, and %EXPORT_TAGS is a hash that defines names for sets of symbols. Names in %EXPORT_TAGS must also appear in @EXPORT or @EXPORT_OK.

Then Perl programs that want to use your module just say:

use Module;                   # Import default symbols
use Module qw(...);           # Import listed symbols
use Module ( );              # Do not import any symbols

The Exporter can handle specialized import lists. An import list is the list of arguments passed to the import method. If the first entry begins with !, :, or /, the list is treated as a series of specifications that add to or delete from the list. A leading ! means delete, rather than add.

Symbol	Meaning
`[!]``name`	This `name` only
`[!]:DEFAULT`	All names in `@EXPORT`
`[!]`:`tag`	All names in `$EXPORT_TAGS{``tag``}` anonymous list
`[!]/``pattern``/`	All names in `@EXPORT` and `@EXPORT_OK` that match `pattern`

Exporter's methods are the following.

export_fail

module_name->export_fail(failed_symbols)

Returns a list of symbols that couldn't be imported. The default method provided by Exporter returns the list unchanged.

export_ok_tags

export_ok_tags(taglist)

Adds tagged sets of symbols to @EXPORT_OK.

export_tags

export_tags(taglist)

Adds tagged sets of symbols to @EXPORT.

export_to_level

package->export_to_level(n, what_to_export)

Used when you can't use Exporter's import method directly. Takes the following arguments:

n: An integer specifying how far up the calling stack to export your symbols
what_to_export: Array of symbols to export, usually @_

import

import

The default import method.

require_version

module_name->require_version(value)

Validates the version of module module_name, checking that it is at least value.