[swift-evolution] [Review] SE-0006 Apply API Guidelines to the Standard Library

Fri Jan 29 09:29:43 CST 2016

I'm fine with "require", especially as I've been introduced to pre- and postconditions by Bertrand Meyer's Eiffel, which uses "require" for preconditions and "ensure" for postconditions and is still the only language that I know that has these baked into the language including proper behavior in the face of inheritance.

-Thorsten 

> Am 27.01.2016 um 01:39 schrieb Dave Abrahams via swift-evolution <swift-evolution at swift.org>:
> 
> 
>> on Tue Jan 26 2016, Charles Kissinger <swift-evolution at swift.org> wrote:
>> 
>> I agree with all of the small criticisms mentioned below by Radoslaw
>> except for the renaming of precondition() to require(). I think it is
>> an improvement that it describes an action now, just like assert().
> 
> Interestingly, I was the one that insisted on that change, as I felt
> “precondition” was too much of a term-of-art and “require” would be more
> accessible, but I am now regretting that decision.  This function is not
> conceptually an action; like “assert,” it's a declarative statement, and
> “precondition” conveyed that aspect much better, IMO.
> 
>> 
>> Count me among those who liked the ‘Type’ suffix for protocols though.
>> 
>> —CK
>> 
>>> On Jan 25, 2016, at 7:40 AM, Radosław Pietruszewski via
>>> swift-evolution
>>> <swift-evolution at swift.org> wrote:
>>> 
>>> Hello all,
>>> 
>>> Just like with SE-0005
>>> <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160125/007658.html>,
>>> I’m overwhelmingly for this proposal. The Guidelines, as a whole do
>>> a great job at making Swift APIs more consistent and clearer, and
>>> applying them to the Swift stdlib is an important first step.
>>> 
>>> * * *
>>> 
>>> Nitpicks, criticisms and suggestions:
>>> 
>>> == precondition was renamed to require ==
>>> 
>>> This might be confusing to newcomers, as many languages use the word
>>> `require` as a keyword for what we'd call `import`. Although a bit
>>> more technical, `precondition` is unambiguous and still easily
>>> understandable. I feel like `required` does more damage than good.
>>> 
>>> == Removed Type from protocol names ==
>>> 
>>> Perhaps I’ve missed some discussion about this and I don’t see the
>>> context, but I’m not sure this is a positive change.
>>> 
>>> I fear this might be confusing in practice, at least in some
>>> contexts. For example, there's nothing signifying that "Boolean" or
>>> "Integer" are protocols and not actual types. Same with “Sequence”,
>>> “OptionSet”, etc. Perhaps it doesn't matter because everyone will
>>> naturally go for `Bool`, `Int`, and `Array` anyway. But I can
>>> imagine a lot of confusion if someone tried that anyway, or perhaps
>>> saw that in the autocompletion, or the standard library browser
>>> (with no intention of using the protocol).
>>> 
>>> I’m all for removing unnecessary noise and verbosity, but I think I
>>> would err on explicitness side here. It seemed like the -able/-Type
>>> convention did a good job disambiguating types you can actually
>>> instantiate from protocols, with very little “verbosity cost”.
>>> 
>>> == sort() => sorted(), sortInPlace() => sort() etc ==
>>> 
>>> I’m torn on this.
>>> 
>>> Frankly, I find both the “foo/fooInPlace” and “bar/barred”
>>> conventions awkward. Both seem weird. “InPlace” isn’t something I
>>> recall seeing anywhere else in API naming, and seems a bizarre way
>>> of signifying mutability. “-ed” doesn’t work with all words, so you
>>> sometimes have to go with “-ing”, or give up and cry. And then you
>>> have inconsistency that “-InPlace” doesn’t seem to have. Also,
>>> -ed/-ing can sometimes be difficult to write, especially for
>>> non-natives because of the “last letter is doubled” rule for some
>>> words.
>>> 
>>> But my biggest problem with this change is that IMHO we should
>>> encourage to use the transforming (non-mutating) variants by
>>> default. One way to achieve this as an API designer and slightly
>>> push people towards doing what’s considered best practice is to make
>>> the preferable variant easier to type. This might be a subtle
>>> change, but I think it matters. Before, if you really wanted to
>>> mutate something in place, you had to do that extra little bit of
>>> work typing “sortInPlace”, whereas what would be preferable most of
>>> the time had a simpler, shorter form: “sort” and would appear
>>> earlier in autocomplete.
>>> 
>>> == -ings in argument names ==
>>> 
>>> I’ve noticed these few tweaks in naming:
>>> 
>>>> -  mutating func removeAll(keepCapacity keepCapacity: Bool = false)
>>>> +  mutating func removeAll(keepingCapacity keepingCapacity: Bool = false)
>>>> 
>>>> public func transcode<...>(...
>>>> -  stopOnError: Bool
>>>> +  stoppingOnError: Bool
>>>> ) -> Bool
>>>> 
>>>> +  public init(allocatingCapacity count: Int)
>>> 
>>> I'm against this change. While I'm not fully convinced of the
>>> -ed/-ing rule for methods and properties, it does an important job
>>> by conveying the non-mutating semantics of a symbol described. In
>>> case of argument names, this rationale no longer applies.
>>> 
>>> The only reason to write "stoppingOnError" instead of "stopOnError"
>>> is to make method invocations sound more like real English
>>> sentences. This is the conventional Objective-C thinking the
>>> Guidelines largely step back from. In my opinion, this is futile and
>>> provides no readability benefits in this context. Method invocations
>>> are _not_ sentences. It's not English, it's code. And while making
>>> method names blatantly gramatically incorrect doesn't help
>>> readability, neither does forcing `-ing` endings to all boolean
>>> function arguments.
>>> 
>>> The only thing it does is it adds a few extra characters, an extra
>>> word ending the reader has to parse and understand. I know that it's
>>> a non-goal to make Swift code as terse as possible, and I'm not
>>> arguing for that. But the Guidelines seem to agree that adding extra
>>> verbosity _without a good reason_ is a bad thing. Because every
>>> extra word and symbol in code just adds to the cognitive load of the
>>> reader. And when it doesn't serve a purpose, it just decreases the
>>> signal-to-noise ratio.
>>> 
>>> Plus, as mentioned before, `-ed/-ing` can be tricky to spell for
>>> non-natives. This might not be a big deal, but given that this
>>> change provides no benefits, it's one more tiny thing you have to be
>>> careful not to get wrong when writing Swift.
>>> 
>>> And it's unnecessary:
>>> 
>>>   removeAll(keepCapacity: true)
>>>   transcode(foo, bar, stopOnError: true)
>>> 
>>> Are just as clear and readable as:
>>> 
>>>   removeAll(keepingCapacity: true)
>>>   transcode(foo, bar, stoppingOnError: true)
>>> 
>>> And the former isn't gramatically incorrect, because this isn't a sentence.
>>> 
>>> Apologies for nitpicking on this tiniest possible detail. I just
>>> care a lot that we don't create a precedent of trying to make
>>> everything sound like English unnecessarily and add verbosity bit by
>>> bit.
>>> 
>>> * * *
>>> 
>>>> Is the problem being addressed significant enough to warrant a change to Swift?
>>>> Does this proposal fit well with the feel and direction of Swift?
>>> Yes, and yes, with small details still worth reconsidering.
>>> 
>>>> How much effort did you put into your review? A glance, a quick
>>>> reading, or an in-depth study?
>>> 
>>> I’ve read the whole proposal, as well as the related proposals, and
>>> read the thread for this review.
>>> 
>>> Cross-linking to my SE-0005 review:
>>> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160125/007658.html
>>> <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160125/007658.html>
>>> 
>>> Thanks,
>>> — Radek
>>> 
>>>> On 22 Jan 2016, at 22:02, Douglas Gregor via swift-evolution
>>>> <swift-evolution at swift.org
>>>> <mailto:swift-evolution at swift.org>>
>>>> wrote:
>>>> 
>>>> Hello Swift community,
>>>> 
>>>> The review of SE-0006 "Apply API Guidelines to the Standard
>>>> Library" begins now and runs through January 31, 2016. The proposal
>>>> is available here:
>>>> 
>>>> https://github.com/apple/swift-evolution/blob/master/proposals/0006-apply-api-guidelines-to-the-standard-library.md
>>>> <https://github.com/apple/swift-evolution/blob/master/proposals/0006-apply-api-guidelines-to-the-standard-library.md>
>>>> Reviews are an important part of the Swift evolution process. All
>>>> reviews should be sent to the swift-evolution mailing list at
>>>> 
>>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>>> <https://lists.swift.org/mailman/listinfo/swift-evolution>
>>>> or, if you would like to keep your feedback private, directly to
>>>> the review manager. When replying, please try to keep the proposal
>>>> link at the top of the message:
>>>> 
>>>> Proposal link:
>>>> 
>>>> https://github.com/apple/swift-evolution/blob/master/proposals/0006-apply-api-guidelines-to-the-standard-library.md
>>>> <https://github.com/apple/swift-evolution/blob/master/proposals/0006-apply-api-guidelines-to-the-standard-library.md>
>>>> Reply text
>>>> 
>>>> Other replies
>>>> <https://github.com/apple/swift-evolution#what-goes-into-a-review-1>What
>>>> goes into a review?
>>>> 
>>>> The goal of the review process is to improve the proposal under
>>>> review through constructive criticism and, eventually, determine
>>>> the direction of Swift. When writing your review, here are some
>>>> questions you might want to answer in your review:
>>>> 
>>>> What is your evaluation of the proposal?
>>>> Is the problem being addressed significant enough to warrant a change to Swift?
>>>> Does this proposal fit well with the feel and direction of Swift?
>>>> If you have used other languages or libraries with a similar
>>>> feature, how do you feel that this proposal compares to those?
>>>> How much effort did you put into your review? A glance, a quick
>>>> reading, or an in-depth study?
>>>> More information about the Swift evolution process is available at
>>>> 
>>>> https://github.com/apple/swift-evolution/blob/master/process.md
>>>> <https://github.com/apple/swift-evolution/blob/master/process.md>
>>>> Thank you,
>>>> 
>>>> -Doug Gregor
>>>> 
>>>> Review Manager
>>>> 
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>>> 
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> 
> -- 
> -Dave
> 
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