Function.js

/*
 * Based on:
 * Ext JS Library 1.1.1
 * Copyright(c) 2006-2007, Ext JS, LLC.
 *
 * Originally Released Under LGPL - original licence link has changed is not relivant.
 *
 * Fork - LGPL
 * <script type="text/javascript">
 */

(function() {    
    // wrappedn so fnCleanup is not in global scope...
    if(Roo.isIE) {
        function fnCleanUp() {
            var p = Function.prototype;
            delete p.createSequence;
            delete p.defer;
            delete p.createDelegate;
            delete p.createCallback;
            delete p.createInterceptor;

            window.detachEvent("onunload", fnCleanUp);
        }
        window.attachEvent("onunload", fnCleanUp);
    }
})();


/**
 * @class Function
 * These functions are available on every Function object (any JavaScript function).
 */
Roo.apply(Function.prototype, {
     /**
     * Creates a callback that passes arguments[0], arguments[1], arguments[2], ...
     * Call directly on any function. Example: <code>myFunction.createCallback(myarg, myarg2)</code>
     * Will create a function that is bound to those 2 args.
     * @return {Function} The new function
    */
    createCallback : function(/*args...*/){
        // make args available, in function below
        var args = arguments;
        var method = this;
        return function() {
            return method.apply(window, args);
        };
    },

    /**
     * Creates a delegate (callback) that sets the scope to obj.
     * Call directly on any function. Example: <code>this.myFunction.createDelegate(this)</code>
     * Will create a function that is automatically scoped to this.
     * @param {Object} obj (optional) The object for which the scope is set
     * @param {Array} args (optional) Overrides arguments for the call. (Defaults to the arguments passed by the caller)
     * @param {Boolean/Number} appendArgs (optional) if True args are appended to call args instead of overriding,
     *                                             if a number the args are inserted at the specified position
     * @return {Function} The new function
     */
    createDelegate : function(obj, args, appendArgs){
        var method = this;
        return function() {
            var callArgs = args || arguments;
            if(appendArgs === true){
                callArgs = Array.prototype.slice.call(arguments, 0);
                callArgs = callArgs.concat(args);
            }else if(typeof appendArgs == "number"){
                callArgs = Array.prototype.slice.call(arguments, 0); // copy arguments first
                var applyArgs = [appendArgs, 0].concat(args); // create method call params
                Array.prototype.splice.apply(callArgs, applyArgs); // splice them in
            }
            return method.apply(obj || window, callArgs);
        };
    },

    /**
     * Calls this function after the number of millseconds specified.
     * @param {Number} millis The number of milliseconds for the setTimeout call (if 0 the function is executed immediately)
     * @param {Object} obj (optional) The object for which the scope is set
     * @param {Array} args (optional) Overrides arguments for the call. (Defaults to the arguments passed by the caller)
     * @param {Boolean/Number} appendArgs (optional) if True args are appended to call args instead of overriding,
     *                                             if a number the args are inserted at the specified position
     * @return {Number} The timeout id that can be used with clearTimeout
     */
    defer : function(millis, obj, args, appendArgs){
        var fn = this.createDelegate(obj, args, appendArgs);
        if(millis){
            return setTimeout(fn, millis);
        }
        fn();
        return 0;
    },
    /**
     * Create a combined function call sequence of the original function + the passed function.
     * The resulting function returns the results of the original function.
     * The passed fcn is called with the parameters of the original function
     * @param {Function} fcn The function to sequence
     * @param {Object} scope (optional) The scope of the passed fcn (Defaults to scope of original function or window)
     * @return {Function} The new function
     */
    createSequence : function(fcn, scope){
        if(typeof fcn != "function"){
            return this;
        }
        var method = this;
        return function() {
            var retval = method.apply(this || window, arguments);
            fcn.apply(scope || this || window, arguments);
            return retval;
        };
    },

    /**
     * Creates an interceptor function. The passed fcn is called before the original one. If it returns false, the original one is not called.
     * The resulting function returns the results of the original function.
     * The passed fcn is called with the parameters of the original function.
     * @addon
     * @param {Function} fcn The function to call before the original
     * @param {Object} scope (optional) The scope of the passed fcn (Defaults to scope of original function or window)
     * @return {Function} The new function
     */
    createInterceptor : function(fcn, scope){
        if(typeof fcn != "function"){
            return this;
        }
        var method = this;
        return function() {
            fcn.target = this;
            fcn.method = method;
            if(fcn.apply(scope || this || window, arguments) === false){
                return;
            }
            return method.apply(this || window, arguments);
        };
    }
});