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diff --git a/tools/addon-sdk-1.7/packages/api-utils/docs/traits.md b/tools/addon-sdk-1.7/packages/api-utils/docs/traits.md new file mode 100644 index 0000000..910cd9a --- /dev/null +++ b/tools/addon-sdk-1.7/packages/api-utils/docs/traits.md @@ -0,0 +1,244 @@ +<!-- This Source Code Form is subject to the terms of the Mozilla Public + - License, v. 2.0. If a copy of the MPL was not distributed with this + - file, You can obtain one at http://mozilla.org/MPL/2.0/. --> + +<!-- contributed by Irakli Gozalishvil [gozala@mozilla.com] --> + +The `traits` module provides base building blocks for secure object +composition. It exports base trait / constructor function that +constructs an instance of `Trait`. + +[Traits](http://en.wikipedia.org/wiki/Trait_%28computer_science%29) are a +simple composition mechanism for structuring object-oriented programs. Traits +are similar to +[interfaces](http://en.wikipedia.org/wiki/Interface_%28object-oriented_programming%29), +except that they often define only a part of an object's data and behavior and +are intended to be used in conjunction with other traits to completely define +the object. + +Traits are also considered to be a more robust alternative to +[mixins](http://en.wikipedia.org/wiki/Mixins) because, name conflicts have to +be resolved explicitly by composer & because trait composition is +order-independent (hence more declarative). + + +There are some other implementations of traits in JavaScript & some ideas / +APIs are borrowed from them: + +- [traitsjs](http://www.traitsjs.org/) +- [joose](http://code.google.com/p/joose-js/) + +Object-capability security model +-------------------------------- + +Implementation uses an +[object-capability security model](http://en.wikipedia.org/wiki/Object-capability_model) +to allow protection of private APIs. At the same private APIs can be shared +between among trait composition parties. To put it simply: All the properties +whose names start with `"_"` are considered to be **private**, and are +unaccessible from anywhere except other **public** methods / accessors of the +instance that had been defined during composition. + +<api name="Trait"> +@class +<api name="Trait"> +@constructor +Creates an instance of Trait and returns it if it has no `constructor` method +defined. If instance has `constructor` method, then it is called with all the +arguments passed to this function and returned value is returned instead, +unless it's `undefined`. In that case instance is returned. + +`Trait` function represents a base trait. As with any other trait it represents +a constructor function for creating instances of its own & a placeholder +for a trait compositions functions. +</api> + +<api name="compose"> +@method +Composes new trait out of itself and traits / property maps passed as an +arguments. If two or more traits / property maps have properties with the same +name, the new trait will contain a "conflict" property for that name (see +examples in Examples section to find out more about "conflict" properties). +This is a commutative and associative operation, and the order of its +arguments is not significant. + +**Examples:** + +Let's say we want to define a reusable piece of code for a lists of elements. + + var { Trait } = require('traits'); + var List = Trait.compose({ + // private API: + _list: null, + // public API + constructor: function List() { + this._list = []; + }, + get length() this._list.length, + add: function add(item) this._list.push(item), + remove: function remove(item) { + let list = this._list; + let index = list.indexOf(item); + if (0 <= index) list.splice(index, 1); + } + }); + +Instances of `List` can be created by calling `List` function with or without +`new` keyword. + + let l1 = List(); + l1 instanceof List; // true + let l2 = new List(); + l2 instanceof List; // true + +As you can see `add` and `remove` functions are capable of accessing private +`_list` property, but thats about it, there's nothing else that will be able +to access this property: + + '_list' in l1; // false + '_list' in l2; // false + '_list' in List.protoype; // false + l1.has = function(name) name in this + l1.has('_list'); // false + l1.length; // 0 + l1.add('test') + l1.length // 1 + +@param trait1 {Object|Function} + Trait or property map to compose new trait from. +@param trait2 {Object|Function} + Trait or property map to compose new trait from. +@param ... {Object|Function} + Traits or property maps to compose new trait from. + +@returns {Function} + New trait containing the combined properties of all the traits. +</api> + +<api name="required"> +@property {Object} +Singleton, used during trait composition to define "required" properties. + +**Example:** + + var Enumerable = Trait.compose({ + list: Trait.required, + forEach: function forEach(consumer) { + return this.list.forEach(consumer); + } + }); + + let c1 = Enumerable(); // Error: Missing required property: list + + var EnumerableList = List.compose({ + get list() this._list.slice(0) + }, Enumerable); + + let c2 = EnumerableList(); + c2.add('test') + c2.length // 1 + c2.list[0] // 'test' + c2.forEach(console.log) // > info: 'test 0 test' + +</api> + + +<api name="resolve"> +@method +Composes a new trait that has all the same properties +as the trait on which it is called, except that each property listed +in the `resolutions` argument will be renamed from the name +of the property in the `resolutions` argument to its value. +And if its value is `null`, the property will become required. + +**Example:** + + var Range = List.resolve({ + constructor: null, + add: '_add', + }).compose({ + min: null, + max: null, + get list() this._list.slice(0), + constructor: function Range(min, max) { + this.min = min; + this.max = max; + this._list = []; + }, + add: function(item) { + if (item <= this.max && item >= this.min) + this._add(item) + } + }); + + + let r = Range(0, 10); + r.min; // 0 + r.max; // 10 + r.length; // 0; + r.add(5); + r.length; // 1 + r.add(12); + r.length; // 1 (12 was not in a range) + +@param resolutions {Object} +@returns {Function} + New resolved trait. +</api> + +<api name="override"> +@method +Composes a new trait with all of the combined properties of `this` and the +argument traits. In contrast to `compose`, `override` immediately resolves +all conflicts resulting from this composition by overriding the properties of +later traits. Trait priority is from left to right. I.e. the properties of +the leftmost trait are never overridden. + +**Example:** + + // will compose trait with conflict property 'constructor' + var ConstructableList = List.compose({ + constructor: function List() this._list = Array.slice(arguments) + }); + // throws error with message 'Remaining conflicting property: constructor' + ConstructableList(1, 2, 3); + + var ConstructableList = List.override({ + constructor: function List() this._list = Array.slice(arguments) + }); + ConstructableList(1, 2, 3).length // 3 + +@param trait1 {Object|Function} + Trait or property map to compose new trait from. +@param trait2 {Object|Function} + Trait or property map to compose new trait from. +@param ... {Object|Function} + Traits or property maps to compose new trait from. + +@returns {Function} + New trait containing the combined properties of all the traits. +</api> + +<api name="_public"> +@property {Object} +Internal property of instance representing public API that is exposed to the +consumers of an instance. +</api> + +<api name='toString'> +@method +Textual representation of an object. All the traits will return: +`'[object Trait]'` string, unless they have `constructor` property, in that +case string `'Trait'` is replaced with the name of `constructor` property. + +**Example:** + + var MyTrait = Trait.compose({ + constructor: function MyTrait() { + // do your initialization here + } + }); + MyTrait().toString(); // [object MyTrait] + +</api> +</api> |