Garrett: are the guy from ThoughtWorks? if so i read your bio i totally
understand why you write the way you do.
Garrett graduated with honors from Northwestern University with a bachelors of
science in chemical and biological engineering concentrating in process control
computer programming
I studied chemistry so i think with this info we can understand each other
better, avoid conflicts and become more participative than defensive.
On Dec 26, 2010, at 2:36 AM, Garrett Smith wrote:
> On 12/25/10, fernando trasvina <trasv...@gmail.com> wrote:
>>
>> On Dec 24, 2010, at 8:44 PM, Garrett Smith wrote:
>>
>>> On 12/24/10, fernando trasvina <trasv...@gmail.com> wrote:
>>>>
>>>> On Dec 24, 2010, at 6:43 PM, Garrett Smith wrote:
>>>>
>>>>> On 12/24/10, Michael Haufe (TNO) <t...@thenewobjective.com> wrote:
>>>>>> On Dec 24, 3:05 pm, Garrett Smith <dhtmlkitc...@gmail.com> wrote:
>>>>>>
>>>>>>> I rather have it one way or the other. e.g.
>>>>>>>
>>>>>>> makePoint(x, y);
>>>>>>>
>>>>>>> - OR -
>>>>>>>
>>>>>>> new Point(x, y);
>>>>>>>
>>>>>>> I just don't like seeing any extra if/else in the code. I also don't
>>>>>>> want to handle the case where somebody might be relying on an anomaly
>>>>>>> of calling the constructor as a function call.
>>>>>>
>>>>>> If defensive programming isn't necessary, of course. But since JS
>>>>>> can't statically enforce such things it may be necessary to do so.
>>>>>>
>>>>> If a factory is used, then that's irrelevant. Toy example:
>>>>>
>>>>> function getAPoint(x, y) {
>>>>>
>>>>> }
>>>>> The worst the client could do would be to use `new getAPoint`. That
>>>>> would be a problem if the API expects `this` to be global object.
>>>>>
>>>>> Methods can be shared in scope, but the x and y properties can be
>>>>> instance properties.
>>>>>
>>>>> function getAPoint(x, y) {
>>>>> function distanceFromOrigin() {
>>>>> return Math.sqrt((this.x * this.x) + (this.y * this.y));
>>>>> }
>>>>> getAPoint = function(x, y) {
>>>>> return {
>>>>> x : x,
>>>>> y : y,
>>>>> distanceFromOrigin: distanceFromOrigin
>>>>> };
>>>>> };
>>>>> return getAPoint(x, y);
>>>>> }
>>>>> getAPoint(4, 0).distanceFromOrigin();
>>>>
>>>> I would say that coding this way should not be done unless there is an
>>>> extreme requirement for it.
>>>>>
>>>>> The downside to that is `distanceFromOrigin` is hanging off the VO, so
>>>>> it looks like a private static method, so what is `this`?
>>>>>
>>>>> It might be OK to "leak" a little implementation detail in this case:
>>>>>
>>>>> function getAPoint(x, y) {
>>>>> function Point(x, y) {
>>>>> this.x = +x;
>>>>> this.y = +y;
>>>>> }
>>>>> Point.prototype = {
>>>>> distanceFromOrigin : function() {
>>>>> return Math.sqrt((this.x * this.x) + (this.y * this.y));
>>>>> }
>>>>> };
>>>>>
>>>>> getAPoint = function(x, y) {
>>>>> return new Point(x, y);
>>>>> };
>>>>>
>>>>> return getAPoint(x, y);
>>>>> }
>>>>
>>>> this should be done this way. you should not be defining the constructor
>>>> function every time you run your factory,
>>>
>>> You're making a statement about the code that is false. The example
>>> uses a technique that is known as "function rewriting" or "russian
>>> doll" or I've explained it with more elaboration below.
>>>
>>> this what is
>>>> really doing is creating a new constructor function every time and
>>>> building
>>>> an instance for it completely useless because because
>>>> then how would you do instanceof? never put this type of closures for
>>>> factories unless really needed.
>>>>
>>>
>>> Your conclusion follows your analysis, which unfortunately is
>>> incorrect. Please see my explanation below.
>>>
>>>> var Point = function(){};
>>>>
>>>> var getAPoint = function(x,y){
>>>> return new Point(x,y);
>>>> }
>>>>
>>> What's missing from that example?
>> are you making up a point of a rhetorical question in here? nothing is
>> missing, you can run the code and get an instance of Point
>>
>
> The Point constructor doesn't really do anything. It looks like you
> forgot something. And you obviously forgot a semicolon after
> `getAPoint`.
>
>
>> please run it and you will se that this is correct
>>
>> alert (getAPoint(1,2) instanceof Point);
>>
>> it is pointless to write the implementation of Point because it is not
>> needed to probe that the resultant object is correct.
>>
>
> Yeah, pointless.
>
>>>
>>> Here is my explanation:
>>>>>
>>>>> The Point constructor is cached on the VO of the outer getAPoint.
>>>>> Outer getAPoint identifier gets assigned to inner getAPoint identifier
>>>>> but the scope chain of the inner getAPoint function has the Point
>>>>> constructor and prototype.
>>
>> OMG lectures again?
>>
>
> Well, if you don't want to learn it, then you don't have to.
>
>> just run your code
>
> Be sure, I run my code before posting.
>
>>
>> function getAPoint(x, y) {
>> function Point(x, y) {
>> this.x = +x;
>> this.y = +y;
>> }
>> Point.prototype = {
>> distanceFromOrigin : function() {
>> return Math.sqrt((this.x * this.x) + (this.y * this.y));
>> }
>> };
>>
>> getAPoint = function(x, y) {
>> return new Point(x, y);
>> };
>>
>> return getAPoint(x, y);
>> }
>>
> I ran that.
>
> I did not run the following, as it is not my code:
>> console.log(getAPoint(1,2)) //Object { x=1, y=2}
>> console.log(getAPoint(1,2) instanceof Point) //false
>>
>
> That's your code not mine. And it does not do what you said it does.
> That code should result ReferenceError, as Point would not be resolved
> there. Well, unless you added a separate Point constructor and got
> yourself confused while typing into FB.
>
>> please check that you so called function rewriting is accomplished by
>> returning tthe execution of inner getPoint which results always in an
>> instance of inner Point, which is useless for introspection.
>>
>
> The inner Point? Again there's only one Point constructor in the example.
>
> [snip massive overquote with signatures]
> --
> Garrett
>
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