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Re: silly question on closure

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Stefan Weiss wrote:

> On 2012-09-24 01:10, Thomas 'PointedEars' Lahn wrote:
>> Stefan Weiss wrote:
>>> On 2012-09-22 14:04, justaguy wrote:
>>>> The closure takes so many lines while the function has only 2 lines to
>>>> get the same thing done.  So, the question is, why do we use closure?
>>> 
>>> You don't, just like you don't actually use "Hello, world" in production
>>> code. This was obviously just an example for how closures work. If this
>>> was code intended for actual use, your "just a function" variant would
>>> be better suited (provided it only returned the value, like in the
>>> "closure" example).
>> 
>> You are mistaken as you are overlooking that creating that Array instance
>> and populating it with elements requires resources – memory and runtime.
>> Since we have only automated garbage collection, and the function may be
>> called a number of times, it is better to use a closure here, so that the
>> object would only be created, and the array only populated, once.
> 
> I would say that depends on the use case.

Of course it does.

> I have no doubt that closures can offer performance benefits even with a
> simple 4-element array like this, but unless you're running the function a
> million times in a tight loop, the difference will be hardly noticable.

Of course.  You are missing the point.

> There's a often a tradeoff between legibility and performance.
> Introducing temporary variables, helper functions, layers of
> indirection, etc, can all hurt performance, but we still do it because
> it helps us keep our code clean, understandable, and maintainable.

False dichotomy.

> In the vast majority of cases, JS performance is not a problem
> (anymore).

You are very much mistaken.

> In this particular case, the goal was "understanding closures". It's a
> fair assumption to make that the code was not running in a tight loop, and
> that the OP was not overly troubled by the performance of his script.

I have disputed your assertion that closures are to be avoided with a two-
line function because they would not be worth it in any case.

> You're writing a general purpose library, the OP is learning JS. Your
> goals are different. Recommending the closure style whenever possible,
> regardless of circumstances, smacks of premature optimization.

Which is why I am not doing that.


PointedEars
-- 
    realism:    HTML 4.01 Strict
    evangelism: XHTML 1.0 Strict
    madness:    XHTML 1.1 as application/xhtml+xml
                                                    -- Bjoern Hoehrmann

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silly question on closure justaguy <lichunshen84@gmail.com> - 2012-09-22 05:04 -0700
  Re: silly question on closure Stefan Weiss <krewecherl@gmail.com> - 2012-09-22 18:18 +0200
    Re: silly question on closure justaguy <lichunshen84@gmail.com> - 2012-09-22 18:41 -0700
    Re: silly question on closure Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-24 01:10 +0200
      Closures (was: silly question on closure) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-24 13:14 +0200
      Re: silly question on closure Stefan Weiss <krewecherl@gmail.com> - 2012-09-27 05:04 +0200
        Re: silly question on closure Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-27 20:50 +0200
          Re: silly question on closure Stefan Weiss <krewecherl@gmail.com> - 2012-09-27 21:29 +0200
  Re: silly question on closure "Tom de Neef" <tdeneef@qolor.nl> - 2012-09-22 20:00 +0200
    Re: silly question on closure justaguy <lichunshen84@gmail.com> - 2012-09-22 18:42 -0700
      Re: silly question on closure justaguy <lichunshen84@gmail.com> - 2012-09-23 07:31 -0700
        Re: silly question on closure Stefan Weiss <krewecherl@gmail.com> - 2012-09-23 18:49 +0200
          Re: silly question on closure justaguy <lichunshen84@gmail.com> - 2012-09-23 13:33 -0700
          Re: silly question on closure justaguy <lichunshen84@gmail.com> - 2012-09-23 13:38 -0700
            Re: silly question on closure Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-24 20:49 +0200
    Re: silly question on closure Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-24 01:14 +0200
  Re: silly question on closure dann90038@gmail.com - 2012-09-23 15:37 -0700

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