NAME¶
Perl6::Export::Attrs - The Perl 6 'is export(...)' trait as a Perl 5 attribute
VERSION¶
This document describes Perl6::Export::Attrs version 0.0.3
SYNOPSIS¶
package Some::Module;
use Perl6::Export::Attrs;
# Export &foo by default, when explicitly requested,
# or when the ':ALL' export set is requested...
sub foo :Export(:DEFAULT) {
print "phooo!";
}
# Export &var by default, when explicitly requested,
# or when the ':bees', ':pubs', or ':ALL' export set is requested...
# the parens after 'is export' are like the parens of a qw(...)
sub bar :Export(:DEFAULT :bees :pubs) {
print "baaa!";
}
# Export &baz when explicitly requested
# or when the ':bees' or ':ALL' export set is requested...
sub baz :Export(:bees) {
print "baassss!";
}
# Always export &qux
# (no matter what else is explicitly or implicitly requested)
sub qux :Export(:MANDATORY) {
print "quuuuuuuuux!";
}
IMPORT {
# This block is called when the module is used (as usual),
# but it is called after any export requests have been handled.
# Those requests will have been stripped from its @_ argument list
}
DESCRIPTION¶
Implements a Perl 5 native version of what the Perl 6 symbol export mechanism
will look like.
It's very straightforward:
- •
- If you want a subroutine to be capable of being exported (when explicitly
requested in the "use" arguments), you mark it with the
":Export" attribute.
- •
- If you want a subroutine to be automatically exported when the module is
used (without specific overriding arguments), you mark it with the
":Export(:DEFAULT)" attribute.
- •
- If you want a subroutine to be automatically exported when the module is
used (even if the user specifies overriding arguments), you mark it with
the ":Export(:MANDATORY)" attribute.
- •
- If the subroutine should also be exported when particular export groups
are requested, you add the names of those export groups to the attribute's
argument list.
That's it.
"IMPORT" blocks¶
Perl 6 replaces the "import" subroutine with an "IMPORT"
block. It's analogous to a "BEGIN" or "END" block, except
that it's executed every time the corresponding module is "use"'d.
The "IMPORT" block is passed the argument list that was specified on
the "use" line that loaded the corresponding module. However, any
export specifications (names of subroutines or tagsets to be exported) will
have already been removed from that argument list before "IMPORT"
receives it.
DIAGNOSTICS¶
- %s does not export: %s\nuse %s failed
- You tried to import the specified subroutine, but the module didn't export
it. Often caused by a misspelling, or forgetting to add an
":Export" attribute to the definition of the subroutine in
question.
- Bad tagset in :Export attribute at %s line %s: [%s]
- You tried to import a collection of subroutines via a tagset, but the
module didn't export any subroutines under that tagset. Is the tagset name
misspelled (maybe you forgot the colon?).
- Internal error: missing symbol for %s
- A subroutine was specified as being exported during module compilation but
mysteriously ceased to exist before the module was imported.
CONFIGURATION AND ENVIRONMENT¶
Perl6::Export::Attrs requires no configuration files or environment variables.
DEPENDENCIES¶
This module requires the Attribute::Handlers module to handle the attributes.
INCOMPATIBILITIES¶
None reported.
BUGS AND LIMITATIONS¶
No bugs have been reported. Note that the module does not support exporting
variables. This is considered a
feature, not a bug. See Chapter 17 of
Perl Best Practices (O'Reilly, 2005).
Please report any bugs or feature requests to
"bug-perl6-export-attrs@rt.cpan.org", or through the web interface
at <
http://rt.cpan.org>.
AUTHOR¶
Damian Conway "<DCONWAY@cpan.org>"
LICENCE AND COPYRIGHT¶
Copyright (c) 2005, Damian Conway "<DCONWAY@cpan.org>". All
rights reserved.
This module is free software; you can redistribute it and/or modify it under the
same terms as Perl itself.
DISCLAIMER OF WARRANTY¶
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE
SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE
STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE
SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR
IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO
THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE
PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR
CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY
COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE
SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO
LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR
THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER
SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.