On Dec 25, 2010, at 9:27 PM, Michael Haufe (TNO) wrote:
> On Dec 24, 9:38 pm, Garrett Smith <dhtmlkitc...@gmail.com> wrote:
>> On 12/24/10, Michael Haufe (TNO) <t...@thenewobjective.com> wrote:> On Dec
>> 24, 6:43 pm, Garrett Smith <dhtmlkitc...@gmail.com> wrote:
>>>> The client of the API gets an interface object that has properties and
>>>> methods so instanceof and constructor shouldn't matter.
>>
>>> instanceof is important for an interface consumer to be certain that
>>> they are using the proper object:
>>
>> I disagree.
well this is matter of preferences that should not get into a deeper
discussion beyond discussing why we thing one style is better providing
advantages and lessons learned by which we got to this conclusions.
>>
>>> function draw(group){
>>> if(group instanceof Group){
>>
>> If the program is written so that group then it won't matter. The
>> program can be safe enough to not have to worry about that. Example:
>>
>> var group = createGroup();
>> draw(group);
>>
>> The program would be clear what `group can do at that point. The
>> constructor or prototype wouldn't matter; what matters at that point
>> is what `group` can do.
>>
>> But if you're not sure at any point, then sure, you can use
>> inferential tests like this:
>>
>>> if(typeof group == "object" && typeof group.method1 == "function"
>>> && typeof group.method2 == "function"
>>> && typeof group.method3 == "function"){
>>> //well, it looks like a group....
>>
>> I don't like to see all that into an inline block. It is much less
>> cluttered if the typechecking is moved into a separate function, such
>> as:
>>
>> if(Group.isGroupLike(group)) {> group.method1();
>>> group.method2();
>>> group.method3(); //oops, its not the droid you're looking for
>>> } else {
>>> throw new Error("Shape Group Expected");
>>> }
>>> }
>>
>> Better yet just get rid of the typechecking there.
>>
>> But, when I want to use instanceof, which is rarely, it is inside scope.
> [...]
>
> Well, I can't disagree with a bottom up design choice. Our approaches
> are just simply different.
>
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