From fdb1348b39fcc090f836040ce0a9a83cef41d10a Mon Sep 17 00:00:00 2001 From: rolux Date: Tue, 26 Jun 2012 16:33:50 +0200 Subject: [PATCH] improve design patterns example --- .../ui/widget_design_patterns/js/example.js | 164 +++++++++++++----- 1 file changed, 117 insertions(+), 47 deletions(-) diff --git a/examples/ui/widget_design_patterns/js/example.js b/examples/ui/widget_design_patterns/js/example.js index d8ab3c80..884f0d8a 100644 --- a/examples/ui/widget_design_patterns/js/example.js +++ b/examples/ui/widget_design_patterns/js/example.js @@ -1,7 +1,11 @@ /* -The following examples explain the common design pattern for OxJS UI widgets: an -inheritance model that is neither classical nor prototypal, but "parasitical" (a -term coined by +**Parasitical Inheritance** +*/ +/* +The following examples illustrate the common design pattern for `OxJS` UI +widgets: an inheritance model that is neither classical nor prototypal, but +"parasitical" (a term coined by Douglas Crockford). In a nutshell, "instances" are created by augmenting other instances, but in addition to private members (`var foo`) and public members @@ -14,13 +18,15 @@ be accessed from outside, but since `self` itself is an argument of the /* -Create our own namespace. Not required, but if you wanted to create a -module named `My`, this is how you would do it. +Create our own namespace. Not required, but if we wanted to create a module +named `My`, this is how we would do it. */ Ox.My = {}; /* -
+**Box** +*/ +/* First, lets build the most basic Box widget. A widget is a "constructor" function that takes two (optional) arguments, `options` and `self`, and returns a widget object. It's not a constructor in JavaScript terms though: It doesn't @@ -145,7 +151,9 @@ Ox.My.Box = function(options, self) { }; /* -
+**InvertibleBox** +*/ +/* Now we can "subclass" our Box. Let's build one that can have its color inverted. */ Ox.My.InvertibleBox = function(options, self) { @@ -264,7 +272,9 @@ Ox.My.InvertibleBox = function(options, self) { }; /* -
+**MetaBox** +*/ +/* Now it's time for something more funky: A MetaBox — that is, a box of boxes. */ @@ -273,7 +283,7 @@ Ox.My.MetaBox = function(options, self) { /* This time, we inherit from `Ox.My.InvertibleBox`. The one thing that's different though is the `color` option: It is no longer a single value, but - an array of array of values. That's how the boxes inside out meta-box are + an array of array of values. That's how the boxes inside out MetaBox are specified. The following would create a grid of boxes with two rows and three columns: 
@@ -293,7 +303,7 @@ Ox.My.MetaBox = function(options, self) {
     /*
     But we keep the default color of `Ox.My.InvertibleBox` (`[128, 128, 128]`)
     as our own default color, and only here check if the color option is a
-    single value. In that case, we convert it to an array of one row and one
+    single RGB value. In that case, we convert it to an array of one row and one
     column. This way, whenever someone accidentally passes a single color value,
     our MetaBox can handle it.
     */
@@ -314,10 +324,11 @@ Ox.My.MetaBox = function(options, self) {
     ];
 
     /*
-    `self.$boxes` are the actual boxes. We use `Ox.My.InvertibleBox`, but
-    remove their `doubleclick` handlers, since our meta-box already has one. 
-    (`unbindEvent(event)` removes all handlers, `unbindEvent(event, handler)`
-    removes a specific one.) Then we simply append each box to the meta-box.
+    `self.$boxes` are the actual boxes. We use `Ox.My.InvertibleBox`, but remove
+    the `doubleclick` handlers, since our MetaBox already has one, being an
+    InvertibleBox itself. (`unbindEvent(event)` removes all handlers,
+    `unbindEvent(event, handler)` removes a specific one.) Then we simply append
+    each box to the meta-box.
     */
     self.$boxes = self.options.color.map(function(array, y) {
         return array.map(function(color, x) {
@@ -372,29 +383,42 @@ Ox.My.MetaBox = function(options, self) {
 };
 
 /*
-

+**PixelBox**
+*/
+/*
 The next widget is a peculiar type of meta-box. A PixelBox has only one color,
-but this color will be split into a red box, a green box and a blue box.
+but this color will be split up into a red box, a green box and a blue box.
 */
 Ox.My.PixelBox = function(options, self) {
 
     self = self || {};
-    /*
-    ...
-    */
-    self.options = Ox.extend(Ox.My.Box().defaults(), options || {});
-    var that = Ox.My.MetaBox(Ox.extend(self.options, {
-            color: getColor()
-        }), self)
-        .update({
-            color: setColor
-        });
 
     /*
-    This is how the color gets split up into a red box, a green box and a blue
-    box.
+    The challenge here is that we want our PixelBox to be an instance of
+    `Ox.My.MetaBox`, but with a `color` option like `Ox.My.Box`. So we have to
+    parse the options ourselves, by first extending the defaults of `Ox.My.Box`
+    and then transforming the single-value `color` option into a multi-value
+    `color` option. Calling

+    `Ox.My.PixelBox().options('color')`

+    will now return

+    `[[[128, 0, 0], [0, 128, 0], [0, 0, 128]]]`.
     */
-    function getColor() {
+    self.options = Ox.extend(Ox.My.Box().defaults(), options || {});
+    self.options.color = getColor();
+    /*
+    Now we can pass `self.options` to `Ox.My.MetaBox`.
+    */
+    var that = Ox.My.MetaBox(self.options, self)
+    /*
+    Again, we add a custom handler for `color` updates.
+    */
+        .update({color: setColor});
+
+    /*
+    This is how a single RGB value gets split up into a red box, a green box and
+    a blue box.
+    */
+    function getColor(color) {
         return [[
             [self.options.color[0], 0, 0],
             [0, self.options.color[1], 0],
@@ -403,7 +427,11 @@ Ox.My.PixelBox = function(options, self) {
     }
 
     /*
-    ...
+    When the `color` option gets updated to a new single value, we update it
+    again, this time to multiple values, and return `false` to keep the MetaBox
+    handler from running. We have updated `color`, so our handler will get
+    called again, but now it does nothing, and the MetaBox handler will get
+    invoked.
     */
     function setColor() {
         if (Ox.isNumber(self.options.color[0])) {
@@ -429,12 +457,17 @@ Ox.My.PixelBox = function(options, self) {
         });
     };
 
+    /*
+    And that's the PixelBox.
+    */
     return that;
 
 };
 
 /*
-

+**ImageBox**
+*/
+/*
 And finally — a meta-meta-box! An ImageBox takes an image and, for each
 pixel, displays a PixelBox.
 */
@@ -447,6 +480,12 @@ Ox.My.ImageBox = function(options, self) {
     its `displayText` method.
     */
     var that = Ox.My.Box({}, self).displayText('Loading...');
+    /*
+    It's not required to define empty defaults — omitting them would
+    simply leave them undefined). Still, to add an explicit `null` default is a
+    good practice, as it makes it obvious to any reader of our code that
+    `Ox.My.ImageBox` expects an `image` option.
+    */
     that.defaults(Ox.extend(that.defaults(), {
             image: null
         }))
@@ -500,29 +539,40 @@ Ox.My.ImageBox = function(options, self) {
     We've inherited from `Ox.My.Box`, so we don't have an `invert` method yet.
     This is how we can borrow the one from `Ox.My.MetaBox`. We're passing our
     own `self`, so the `self.$boxes` that the `invert` method of `Ox.My.MetaBox`
-    operates on will be the PixelBoxes that we are assinging in the asynchronous
-    callback above.
+    operates on will be the PixelBoxes that we are assigning in the asynchronous
+    callback above. (This pattern is somewhat analogous to the
+    `someOtherObject.method.apply(this, args)` idiom that is common in
+    JavaScript.)
 
-    This is somewhat analogous to the
-    
-    someOtherObject.method.apply(this, args)
-    

-    pattern that is common in JavaScript.
+    Note that we have to pass `self.options` too, otherwise our own
+    `self.options.size` would get overwritten by the MetaBox default size.
 
-    Note that we have to pass `self.options` too, otherwise our own size would
-    get overwritten by the MetaBox default size.
+    Passing `self` to `Ox.My.MetaBox` has another nice effect: the MetaBox will
+    add its own event handlers to it. So even though `Ox.My.ImageBox` is just an
+    `Ox.My.Box`, it has now inherited `doubleclick` handling from
+    `Ox.My.MetaBox`.
+
+    (Internally, `Ox.Element` stores event handlers in `self`. So what happens
+    is this: `self` gets passed all the way down from `Ox.My.ImageBox` to
+    `Ox.My.MetaBox` to `Ox.My.InvertibleBox` to `Ox.My.Box` to Ox.Element, and
+    when `Ox.My.InvertibleBox` defines its `doubleclick` handler, it ends up on
+    `self`. So when the Ox.Element that is actually in the DOM — the
+    `Ox.My.Box` that `Ox.My.ImageBox` inherits from, which shares the same
+    `self` — receives a `doubleclick`, there is now a handler for it.)
     */
     that.invert = Ox.My.MetaBox(self.options, self).invert;
 
     /*
-    But wait — where's our `doubleclick` handler?
+    And that's it.
     */
     return that;
 
 };
 
 /*
-

+**VideoBox**
+*/
+/*
 This one is left as an exercise to the reader ;)
 */
 Ox.My.VideoBox = function(options, self) {
@@ -530,13 +580,26 @@ Ox.My.VideoBox = function(options, self) {
 };
 
 /*
-

-Load the UI and Image modules.
+**Demo**
+*/
+/*
+Load the Image and UI modules.
 */
 Ox.load(['Image', 'UI'], function() {
+    /*
+    Pick a random color. Ox.rgb will convert HSL to RGB.
+    */
     var h = Ox.random(360), s = 1, l = 0.5;
+    /*
+    Create a global variable, so that we can play with our widgets in the
+    console.
+    */
     window.My = {};
-    My.$backgroundBox = Ox.My.Box({
+    /*
+    Since `Ox.My.Box` is a good multi-purpose container, we create one to
+    contain the first four boxes.
+    */
+    My.$container = Ox.My.Box({
             size: [256, 256]
         })
         .append(
@@ -558,16 +621,23 @@ Ox.load(['Image', 'UI'], function() {
             })
         )
         .appendTo(Ox.$body);
+    /*
+    The ImageBox is a bit larger.
+    */
     My.$imageBox = Ox.My.ImageBox({
             image: 'png/pandora32.png',
             size: [256, 256]
         })
         .appendTo(Ox.$body);
+    /*
+    As a last step, we add a handler to the `invert` event of each widgets. It
+    will display the widget name inside the `Ox.My.Box`.
+    */
     Ox.forEach(My, function($element, name) {
         $element.bindEvent({
             invert: function() {
                 My.$box.displayText(name[1].toUpperCase() + name.slice(2));
             }
-        })
+        });
     });
-});
\ No newline at end of file
+});