Exporter::Easy(3pm) User Contributed Perl Documentation Exporter::Easy(3pm)
NAME
Exporter::Easy - Takes the drudgery out of Exporting symbols
SYNOPSIS
In module YourModule.pm:
package YourModule;
use Exporter::Easy (
OK => [ '$munge', 'frobnicate' ] # symbols to export on request
);
In other files which wish to use YourModule:
use ModuleName qw(frobnicate); # import listed symbols
frobnicate ($left, $right) # calls YourModule::frobnicate
DESCRIPTION
Exporter::Easy makes using Exporter easy. In it's simplest case it allows you to drop the boilerplate code that comes with using Exporter,
so
require Exporter;
use base qw( Exporter );
use vars qw( @EXPORT );
@EXPORT = ( 'init' );
becomes
use Exporter::Easy ( EXPORT => [ 'init' ] );
and more complicated situations where you use tags to build lists and more tags become easy, like this
use Exporter::Easy (
EXPORT => [qw( init :base )],
TAGS => [
base => [qw( open close )],
read => [qw( read sysread readline )],
write => [qw( print write writeline )],
misc => [qw( select flush )],
all => [qw( :base :read :write :misc)],
no_misc => [qw( :all !:misc )],
],
OK => [qw( some other stuff )],
);
This will set @EXPORT, @EXPORT_OK, @EXPORT_FAIL and %EXPORT_TAGS in the current package, add Exporter to that package's @ISA and do a "use
vars" on all the variables mentioned. The rest is handled as normal by Exporter.
HOW TO USE IT
Put
use Exporter::Easy ( KEY => value, ...);
in your package. Arguments are passes as key-value pairs, the following keys are available
TAGS
The value should be a reference to a list that goes like (TAG_NAME, TAG_VALUE, TAG_NAME, TAG_VALUE, ...), where TAG_NAME is a string
and TAG_VALUE is a reference to an array of symbols and tags. For example
TAGS => [
file => [ 'open', 'close', 'read', 'write'],
string => [ 'length', 'substr', 'chomp' ],
hash => [ 'keys', 'values', 'each' ],
all => [ ':file', ':string', ':hash' ],
some => [':all', '!open', ':hash'],
]
This is used to fill the %EXPORT_TAGS in your package. You can build tags from other tags - in the example above the tag "all" will
contain all the symbols from "file", "string" and "hash". You can also subtract symbols and tags - in the example above, "some"
contains the symbols from all but with "open" removed and all the symbols from "hash" removed.
The rule is that any symbol starting with a ':' is taken to be a tag which has been defined previously (if it's not defined you'll get
an error). If a symbol is preceded by a '!' it will be subtracted from the list, otherwise it is added.
If you try to redefine a tag you will also get an error.
All the symbols which occur while building the tags are automatically added your package's @EXPORT_OK array.
OK The value should be a reference to a list of symbols and tags (which will be exapanded). These symbols will be added to the @EXPORT_OK
array in your package. Using OK and and OK_ONLY together will give an error.
OK_ONLY
The value should be a reference to a list of symbols and tags (which will be exapanded). The @EXPORT_OK array in your package will
contains only these symbols.. This totally overrides the automatic population of this array. If you just want to add some symbols to
the list that Exporter::Easy has automatically built then you should use OK instead. Using OK_ONLY and OK together will give an error.
EXPORT
The value should be a reference to a list of symbol names and tags. Any tags will be expanded and the resulting list of symbol names
will be placed in the @EXPORT array in your package. The tag created by the ALL key is not available at this stage.
FAIL
The value should be a reference to a list of symbol names and tags. The tags will be expanded and the resulting list of symbol names
will be placed in the @EXPORT_FAIL array in your package. They will also be added to the @EXPORT_OK list.
ALL The value should be the name of tag that doesn't yet exist. This tag will contain a list of all symbols which can be exported.
ISA If you set this to 0 then Exporter will not be added to your @ISA list.
VARS
If this is set to 1 or not provided then all $, @ and % variables mentioned previously will be available to use in your package as if
you had done a "use vars" on them. If it's set to a reference to a list of symbols and tags then only those symbols will be available.
If it's set to 0 then you'll have to do your own "use vars" in your package.
PROCESSING ORDER
We need take the information provided and build @EXPORT, @EXPORT_OK, @EXPORT_FAIL and %EXPORT_TAGS in the calling package. We may also need
to build a tag with all of the symbols and to make all the variables useable under strict.
The arguments are processed in the following order: TAGS, EXPORT, OK, OK_ONLY and FAIL, ALL, VARS and finally ISA. This means you cannot
use the tag created by ALL anywhere except in VARS (although vars defaults to using all symbols anyway).
SEE ALSO
For details on what all these arrays and hashes actually do, see the Exporter documentation.
AUTHOR
Written by Fergal Daly <fergal@esatclear.ie>.
LICENSE
Under the same license as Perl itself
perl v5.12.4 2004-07-24 Exporter::Easy(3pm)