> On Dec 23, 2016, at 11:07, Xiaodi Wu via swift-evolution
> <[email protected]> wrote:
>
>> On Fri, Dec 23, 2016 at 1:33 PM, Callionica (Swift)
>> <[email protected]> wrote:
>> I support the principle of progressive disclosure. I still fail to see how
>> if class capture were introduced it would prevent people from learning about
>> classes, functions, closures or any other existing concept in whatever order
>> the student or teacher preferred.
>>
>> I disagree that there is any significant risk that a novice user that
>> doesn't expect to be able to use names that are in scope would be worse off
>> with this change. Think about the exact sequence of events that has to occur
>> to trigger this user's confusion. OTOH beginners that expect to be able to
>> use names that are in scope will be better off.
>>
>> In general I don't believe learning has the linearity you suggest and I
>> don't think there is anything particularly natural about the specific
>> sequence of concepts you've listed.
>
> I'm making no claim that learning _has_ to be linear or ought to be, nor that
> any particular sequence of learning is _particularly_ natural. Rather, I
> understand the notion of progressive disclosure to mean that there ought to
> be _some_ sequence or sequences of learning where it is possible to master
> things in a linear fashion _if_ any particular learner wishes to proceed
> linearly, with concepts introduced earlier not making reference to concepts
> learned later. It is entirely fair if someone finds it more intuitive to
> learn or teach the same material in a different order, or even to learn or
> teach multiple concepts simultaneously.
>
> Put another way, the question is not whether it's reasonable to have all
> learners progress through Swift in one particular blessed way. The question
> is whether, _if_ a learner is not yet ready to learn concept Z, it's possible
> to teach unrelated concept Y without reference to Z, for some reasonable
> ordering(s) of concepts from A to Z.
>
> In this analysis, I think that classes capturing variables from a containing
> function would be detrimental. If one considers classes, functions, and
> closures as three topics, it is currently possible (I think) to master
> classes and functions without reference to closures. In a scenario where
> classes can capture variables in a containing function, one must understand
> the concept of escaping closures to master classes and functions. The
> argument isn't that one linear sequence of learning is superior to the
> others; the argument is that a reasonable linear ordering of these concepts
> conducive for at least some learners would become non-linear by having this
> new feature.
>
>> I think it's worthwhile to analyze features from the point of view of
>> beginner users of the language, but I reach the opposite conclusion in this
>> case.
>>
>> -- Callionica
If that's the only objection, couldn't we put it behind a per-file
"#enableScaryFeatures" flag? Maybe up by any import statements, so it's easy to
see? Seems shortsighted to not let advanced programmers use a feature just
because it's tricky for beginners. Or maybe "#enableExperimentalSyntaxes", for
stuff that we know we want, but for which we don't yet have a syntax that's
sufficiently "swifty" for us to commit to it (which would have the added
"benefit" of giving us a place to put any feature whose syntax is a bit
unstable).
(That's it... I don't have much of an opinion one way or the other on the
thread's proposal yet.)
- Dave Sweeris
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