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easejs/lib/class_final.js

102 lines
2.3 KiB
JavaScript

/**
* Wrapper permitting the definition of final classes
*
* Copyright (C) 2011 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 a final class
*
* @return {Function} final class
*/
exports = module.exports = function()
{
markFinal( arguments );
// forward everything to Class
var result = Class.apply( this, arguments );
if ( !Class.isClass( result ) )
{
finalOverride( result );
}
return result;
};
/**
* Creates a final class from a class extend operation
*
* @return {Function} final class
*/
exports.extend = function()
{
markFinal( arguments );
return Class.extend.apply( this, arguments );
};
/**
* Causes a definition to be flagged as final
*
* 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 markFinal( args )
{
// the last argument _should_ be the definition
var dfn = args[ args.length - 1 ];
if ( typeof dfn === 'object' )
{
// mark as abstract
dfn.___$$final$$ = true;
}
}
/**
* Overrides object members to permit final classes
*
* @param {Object} obj object to override
*
* @return {undefined}
*/
function finalOverride( obj )
{
var extend = obj.extend;
// wrap extend, applying the abstract flag
obj.extend = function()
{
markFinal( arguments );
return extend.apply( this, arguments );
};
}