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Class::ParmList - Methods for processing named parameter lists |
Class::ParmList - Methods for processing named parameter lists
use Class::ParmList qw(simple_parms parse_parms);
$thingy->some_method({
-bgcolor => '#ff0000',
-textcolor => '#000000'
});
sub some_method {
my ($self) = shift;
my ($parm_ref) = @_;
my $parms = Class::ParmList->new ({
-parms => $parm_ref,
-legal => [qw (-textcolor -border -cellpadding)],
-required => [qw (-bgcolor)],
-defaults => {
-bgcolor => "#ffffff",
-textcolor => "#000000"
}
});
if (not defined $parms) {
my $error_message = Class::ParmList->error;
die ($error_message);
}
# Stuff...
}
sub another_method {
my $self = shift;
my ($name,$rank,$serial_number) = simple_parms([qw(-name -rank -serial_number)], @_);
#...
}
sub still_another {
my $parms = parse_parms ({
-parms => \@_,
-legal => [qw (-textcolor -border -cellpadding)],
-required => [qw (-bgcolor)],
-defaults => {
-bgcolor => "#ffffff",
-textcolor => "#000000"
}
});
if (not defined $parms) {
my $error_message = Class::ParmList->error;
die ($error_message);
}
# ...
}
This is a simple package for validating calling parameters to a subroutine or method. It allows you to use ``named parameters'' while providing checking for number and naming of parameters for verifying inputs are as expected and meet any minimum requirements. It also allows the setting of default values for the named parameters if omitted.
1.00 1999.06.16 - Initial release
1.01 1999.06.18 - Performance tweaks
1.02 1999.06.21 - Fixing of failure to catch undeclared parm,
removal of 'use attrs qw(method)', and
extension of 'make test' support.
1.03 2000.12.06 - Added exportable class functions 'simple_parms'
and 'parse_parms' and allowed 'stacking' references
for parms to the object to improve calling usage.
1.04 2005.09.18 - Added META.yml, Build.PL, Artistic_License.txt
GPL_License.txt, LICENSE to distribution. Renamed
CHANGES to Changes. Extended build tests to 100%
coverage. Minor refactoring of module for speed.
Seperated documentation into .pod file.
Added POD/POD Coverage tests.
1.05 2006.03.04 - Corrected mis-usage of Carp in error paths that
was causing less than useful error messages.
Added LICENSE and DISCLAIMER sections to
documentation.
Example:
my $parms = Class::ParmList->new ({
-parms => $parm_ref,
-legal => [qw (-textcolor -border -cellpadding)],
-required => [qw (-bgcolor)],
-defaults => {
-bgcolor => "#ffffff",
-textcolor => "#000000"
}
});
All four parameters (-parms, -legal, -required, and -defaults) are optional. It is liberal in that anything defined for a -default or -required is automatically added to the '-legal' list.
If the '-legal' parameter is not _explicitly_ called out, no checking against the legal list is done. If it _is_ explicitly called out, then all -parms are checked against it and it will fail with an error if a -parms parameter is present but not defined in the -legal explict or implict definitions.
To simplify calling routines, the '-parms' parameters is allowed to 'stack' anon list references: [['parm','value']]
This gives a calling routine the ability to parse @_ without jumping through hoops to handle the cases of arrays vs hashes for the passed parameters.
Example:
sub example_sub {
my $parms = Class::ParmList->new({ -parms => \@_,
-legal => [],
-required => ['-file','-data'],
-defaults => {},
});
#... }
This routine would accept *either*
example_sub({ '-file' => 'test', '-data' => 'stuff' });
or
example_sub( '-file' => 'test', '-data' => 'stuff' );
with no code changes.
Example:
my $parms = parse_parms({ -parms => \@_,
-legal => [],
-required => ['-file','-data'],
-defaults => {},
});
value(s) specified in the call line. If
a parameter is not defined, it returns undef. If a set of
'-legal' parameters were declared, it croaks if a parameter
not in the '-legal' set is asked for.
Example: my ($help,$who) = $parms->get('-help','-who');
if ($parms->exists(-help) {
# do stuff
}
Example:
my @parm_names = $parms->list_parms;
In the case of simple numbers and strings, this produces a new copy, in the case of references to hashes and arrays or objects, it returns the references to the original objects.
Example:
my $parms = $parms->all_parms;
Example:
my $error_message = Class::ParmList->error;
die ($error_message);
Examples:
use Class::ParmList qw(simple_parms);
sub some_method {
my $self = shift;
my ($name,$rank) = simple_parms([qw(-name -rank)],@_);
# Now do stuff
}
sub some_function {
my $serial_number = simple_parms([qw(-serial_number)],@_);
# Now do stuff
}
The passed parameter values for parsing this way may be either an anonymous hash of parameters
Example: a_function({ -parm1_name => $parm1_value, -parm2_name => $parm2_value }) )
or a straight list of parameters:
Example: a_function(-parm1_name => $parm1_value, -parm2_name => $parm2_value) )
Note that it *IS* legal for a parameter to be passed with an 'undef' value - it will not trigger an error.
If you need optional parameters, this function is not well suited. You should use the object methods above instead for that case - they are much more flexible (but quite a bit slower and slightly more complex to use).
Its main virtues are that is is simple to use, has rugged error checking for mis-usages and is reasonably fast.
'simple_parms' can be exported by specifying it on the 'use' line.
1.05 2006.03.04
Copyright Benjamin Franz (<URL:http://www.nihongo.org/snowhare/>) and FreeRun Technologies, Inc. (<URL:http://www.freeruntech.com/>). All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under the same terms and conditions as Perl itself.
This means that you can, at your option, redistribute it and/or modify it under either the terms the GNU Public License (GPL) version 1 or later, or under the Perl Artistic License.
See http://dev.perl.org/licenses/
THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
Use of this software in any way or in any form, source or binary, is not allowed in any country which prohibits disclaimers of any implied warranties of merchantability or fitness for a particular purpose or any disclaimers of a similar nature.
IN NO EVENT SHALL I BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION (INCLUDING, BUT NOT LIMITED TO, LOST PROFITS) EVEN IF I HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
Benjamin Franz, <snowhare@nihongo.org>
None known
Memoization of parameter validation for performance.
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Class::ParmList - Methods for processing named parameter lists |