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Re^5: Real life uses for closures. (update: disambiguation)

by LanX (Canon)
on Feb 13, 2013 at 23:25 UTC ( #1018658=note: print w/ replies, xml ) Need Help??


in reply to Re^4: Real life uses for closures. (update: disambiguation)
in thread Real life uses for closures.

> I was also quite happily solving my programming problems in languages that don't support them for 15+ years before I became acquainted with them.

I agree and as I said closures are somehow the other side of the OO coin in allowing encapsulated variables.

Just more elegantly done with less code in most languages.

It's like saying why do we need lexical variables, as long as we care about chosing the right package-namespaces we can achieve the same. True, but most of us don't wanna code Perl4 anymore!

> I've been reading a lot about constructing interpreters and VMs lately, and one thing that seems common to most new ones is the seemingly obligatory inclusion of closures;

I think it's also part of the feature competition. Like "What you have no App to shave your legs on your new smartphone"?

OTOH what I really like about JS is that it does FP (almost¹) excatly like Perl, while Ruby and Python suck at closure side-effects.

IMHO it's far easier to port FP-patterns than OO-patterns, and closures are indispensable for it.²

Saying this you might have noticed that some participants in this thread didn't really know what closure.

So yes you, can be a very efficient programmer w/o closures.

Cheers Rolf

¹) well exactly if you have a dialect allowing to swap var with let.

²) And we have this "one package per file" paradigm, which forbids to just add another encapsulation on the fly. (No fun discussing the perl critic addicts)

IIRC correctly there was a nice thread where GrandFather solved a problem with an embedded mini-class where I used closures... If I can find it, I'll update.


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Re^6: Real life uses for closures. (update: disambiguation)
by BrowserUk (Pope) on Feb 14, 2013 at 00:04 UTC
    I agree and as I said closures are somehow the other side of the OO coin in allowing encapsulated variables.

    Indeed. One of my very early posts here was a OO class that used closures to produce a JS-style prototypical OO mechanism.

    Looking back at it I'm not sure it'll win any plaudits for maintainability, but it was a great tool for learning the power and limitations of closures.

    It's like saying why do we need lexical variables, as long as we care about chosing the right package-namespaces we can achieve the same.

    I appreciate the analogy, but if you look back, I wasn't reaching any conclusions with my thoughts about closures, just examining the evidence.

    As with many other ideas that suddenly gain currency -- despite usually having been around in one form or another since the '60s or early '70s -- I like to examine 'new ideas' every so often and try to see through the theory-wash, marketing speak and hyperbole, and reach my own conclusions as to their usefulness and importance.

    Through this process I have avoided getting swept alone by many a fad that has subsequently shown itself to be of dubious value. I tend to apply the same criteria to most everything in life.

    As far as closures go; I think I reached the conclusion that they are a valuable addition to languages so long as their implementation does not exact too high a price on the performance of the rest of that language.

    Done right, they are a useful addition to the toolbox; but I wouldn't want to throw out (or ham-string performance-wise) too many of the other tools in the box to accommodate them.

    Continuation passing on the other hand seems to exact too high a price.

    I think it's also part of the feature competition.

    That's essentially what I was wondering. Are closures just another 'we must have that too' kick.

    I think they are somewhat more than that.

    Saying this you might have noticed that some participants in this thread didn't really know what closure.

    Indeed. But that is also true of many a dissertation on them that you'll find online.

    But when I first encountered SmallTalk's block arguments; their significance was lost on me also.


    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.

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