framework/js/lib/extend.js
Toby Zerner 930ddf3253 Get rid of extension convenience method
We might reintroduce this later, but for now I want to keep the
extensions API as light as possible and get input before we add stuff
2015-07-20 18:09:37 +09:30

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/**
* Extend an object's method by running its output through a mutating callback
* every time it is called.
*
* The callback accepts the method's return value and should perform any
* mutations directly on this value. For this reason, this function will not be
* effective on methods which return scalar values (numbers, strings, booleans).
*
* Care should be taken to extend the correct object in most cases, a class'
* prototype will be the desired target of extension, not the class itself.
*
* @example
* extend(Discussion.prototype, 'badges', function(badges) {
* // do something with `badges`
* });
*
* @param {Object} object The object that owns the method
* @param {String} method The name of the method to extend
* @param {function} callback A callback which mutates the method's output
*/
export function extend(object, method, callback) {
const original = object[method];
object[method] = function(...args) {
const value = original.apply(this, args);
callback.apply(this, [value].concat(args));
return value;
};
}
/**
* Override an object's method by replacing it with a new function, so that the
* new function will be run every time the object's method is called.
*
* The replacement function accepts the original method as its first argument,
* which is like a call to 'super'. Any arguments passed to the original method
* are also passed to the replacement.
*
* Care should be taken to extend the correct object in most cases, a class'
* prototype will be the desired target of extension, not the class itself.
*
* @example
* override(Discussion.prototype, 'badges', function(original) {
* const badges = original();
* // do something with badges
* return badges;
* });
*
* @param {Object} object The object that owns the method
* @param {String} method The name of the method to override
* @param {function} newMethod The method to replace it with
*/
export function override(object, method, newMethod) {
const original = object[method];
object[method] = function(...args) {
return newMethod.apply(this, [original.bind(this)].concat(args));
};
}