1
0
Fork 0
easejs/lib/class_abstract.js

124 lines
2.9 KiB
JavaScript

/**
* Wrapper permitting the definition of abstract classes
*
* This doesn't actually introduce any new functionality. Rather, it sets a flag
* to allow abstract methods within a class, forcing users to clearly state
* that a class is abstract.
*
* Copyright (C) 2010 Mike Gerwitz
*
* This file is part of ease.js.
*
* ease.js is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* @author Mike Gerwitz
*/
var Class = require( __dirname + '/class' );
/**
* Creates an abstract class
*
* @return {Function} abstract class
*/
module.exports = exports = function()
{
markAbstract( arguments );
// forward everything to Class
var result = Class.apply( this, arguments );
// if we're using the temporary object, then override its methods to permit
// abstract classes
if ( !Class.isClass( result ) )
{
abstractOverride( result );
}
return result;
};
/**
* Creates an abstract class from a class extend operation
*
* @return {Function} abstract class
*/
exports.extend = function()
{
markAbstract( arguments );
return Class.extend.apply( this, arguments );
};
/**
* Creates an abstract class implementing the given members
*
* Simply wraps the class module's implement() method.
*
* @return {Object} abstract class
*/
exports.implement = function()
{
var impl = Class.implement.apply( this, arguments );
abstractOverride( impl );
return impl;
};
/**
* Causes a definition to be flagged as abstract
*
* This function assumes the last argument to be the definition, which is the
* common case, and modifies the object referenced by that argument.
*
* @param {Arguments} args arguments to parse
*
* @return {undefined}
*/
function markAbstract( args )
{
// the last argument _should_ be the definition
var dfn = args[ args.length - 1 ];
if ( typeof dfn === 'object' )
{
// mark as abstract
dfn.___$$abstract$$ = true;
}
}
/**
* Overrides object members to permit abstract classes
*
* @param {Object} obj object to override
*
* @return {undefined}
*/
function abstractOverride( obj )
{
var extend = obj.extend;
// wrap extend, applying the abstract flag
obj.extend = function()
{
markAbstract( arguments );
return extend.apply( this, arguments );
};
}