Declarative object constructor
use Object::Declare ['MyApp::Column', 'MyApp::Param'];
my %objects = declare {
param foo =>
!is global,
is immutable,
valid_values are qw( more values );
column bar =>
field1 is 'value',
field2 is 'some_other_value',
sub_params are param( is happy ), param ( is sad );
};
print $objects{foo}; # a MyApp::Param object
print $objects{bar}; # a MyApp::Column object
# Assuming that MyApp::Column::new simply blesses into a hash...
print $objects{bar}{sub_params}[0]; # a MyApp::Param object
print $objects{bar}{sub_params}[1]; # a MyApp::Param object
This module exports one function, \*(C`declare\*(C', for building named objects with a declarative syntax, similar to how Jifty::DBI::Schema defines its columns.
In list context, \*(C`declare\*(C' returns a list of name/object pairs in the order of declaration (allowing duplicates), suitable for putting into a hash. In scalar context, \*(C`declare\*(C' returns a hash reference.
Using a flexible \*(C`import\*(C' interface, one can change exported helper functions names (declarator), words to link labels and values together (copula), and the table of named classes to declare (mapping):
use Object::Declare declarator => ['declare'], # list of declarators copula => { # list of words, or a map is => '', # from copula to label prefixes, are => '', # or to callback that e.g. turns has => sub { has => @_ }, # "has X" to "has is X" and # "X has 1" to "has is [X => 1]" }, aliases => { # list of label aliases: more => 'less', # turns "is more" into "is less" # and "more is 1" into "less is 1" }, mapping => { column => 'MyApp::Column', # class name to call ->new to param => sub { # arbitrary coderef also works bless(\@_, 'MyApp::Param'); }, };
After the declarator block finishes execution, all helper functions are removed from the package. Same-named functions (such as &is and &are) that existed before the declarator's execution are restored correctly.
If you export the declarator to another package via @EXPORT, be sure to export all mapping keys as well. For example, this will work for the example above:
our @EXPORT = qw( declare column param );
But this will not:
our @EXPORT = qw( declare );
The copula are not turned into functions, so there is no need to export them.
Audrey Tang <[email protected]>
Copyright 2006, 2007 by Audrey Tang <[email protected]>.
This software is released under the \s-1MIT\s0 license cited below. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the \*(L"Software\*(R"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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