142 lines
3.6 KiB
JavaScript
142 lines
3.6 KiB
JavaScript
/**
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* Contains interface module
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*
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* Copyright (C) 2010 Mike Gerwitz
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*
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* This file is part of ease.js.
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*
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* ease.js is free software: you can redistribute it and/or modify it under the
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* terms of the GNU Lesser General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
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* for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @author Mike Gerwitz
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* @package core
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*/
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var util = require( './util' ),
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Class = require( './class' );
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/**
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* Creates an interface
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*
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* @return {Interface} extended interface
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*/
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exports.extend = function()
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{
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return extend.apply( this, arguments );
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};
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/**
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* Default interface implementation
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*
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* @return {undefined}
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*/
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function Interface() {}
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function extend()
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{
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var args = Array.prototype.slice.call( arguments ),
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props = args.pop() || {},
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base = args.pop() || Interface,
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prototype = new base();
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// sanity check
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inheritCheck( prototype );
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var new_interface = function() {};
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util.propCopy( props, prototype, {
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each: function( name, value )
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{
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if ( util.isAbstractMethod( value ) === false )
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{
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throw TypeError(
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"Only abstract methods are permitted within Interface " +
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"definitons"
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);
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}
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},
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} );
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attachExtend( new_interface );
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new_interface.prototype = prototype;
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new_interface.constructor = new_interface;
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// freeze the interface (preventing additions), if supported
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util.freeze( new_interface );
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return new_interface;
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}
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/**
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* Assures that the parent object is a valid object to inherit from
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*
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* This method allows inheriting from any object (note that it will likely cause
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* errors if not an interface), but will place restrictions on objects like
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* Classes that do not make sense to inherit from. This will provide a more
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* friendly error, with suggestions on how to resolve the issue, rather than a
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* cryptic error resulting from inheritance problems.
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*
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* This method will throw an exception if there is a violation.
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*
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* @param {Object} prototype prototype to check for inheritance flaws
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*
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* @return {undefined}
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*/
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function inheritCheck( prototype )
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{
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// if we're inheriting from another interface, then we're good
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if ( prototype instanceof Interface )
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{
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return;
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}
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if ( Class.isClassInstance( prototype ) )
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{
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throw new TypeError(
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"Interfaces cannot extend from classes. Try creating an " +
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"abstract class instead."
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);
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}
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}
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/**
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* Attaches extend method to the given function (interface)
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*
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* @param {Function} func function (interface) to attach method to
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*
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* @return {undefined}
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*/
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function attachExtend( func )
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{
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/**
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* Shorthand for extending interfaces
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*
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* This method can be invoked on the object, rather than having to call
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* Interface.extend( this ).
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*
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* @param {Object} props properties to add to extended interface
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*
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* @return {Object} extended interface
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*/
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util.defineSecureProp( func, 'extend', function( props )
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{
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return extend( this, props );
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});
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}
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