[swift-evolution] [swift-dev] SE-0047 - Defaulting non-Void functions so they warn on unused results

[Zach Waldowski]

If you're engaging in a non-standard design pattern, that you are
willfully writing yourself, I really don't see what the problem is with
applying @discardableResult to declarations that need it, just like any
of Swift's other decorators that describe convention and use patterns.

Cheers,
  Zach


On Sun, Oct 30, 2016, at 01:52 PM, Jody Schofield via swift-evolution wrote:
> I think assumptions are being made that shouldn't be. For example I
> use a lot for design patterns such as the builder. Most of the methods
> return a reference to self so they can be chained together. The
> compiler shouldn't tell me I'm wrong for ignoring those return values.
> It use to be my decision.
> Swift was already a very opinionated language and I can see it's being
> taken even further. A mistake in my opinion and one that is certainly
> making the language more frustrating than pleasurable to use.
>
>
>
> On Oct 30, 2016, at 1:32 PM, Robert Widmann
> <devteam.codafi at gmail.com> wrote:
>> Functions that return values return them for a reason.  Ignoring them
>> is, more likely than not, an oversight that should be corrected,
>> hence @discardableResult.  We're talking error codes, object lifetime
>> tokens, failure indicators, etc.  All things that result in ignoring
>> critical code paths for the sake of convenience.  If you find
>> yourself executing a lot of side effects and ignoring return values,
>> I would take a look at why.  A lot of times you have control over the
>> API and can eliminate some of these unused return values.  Otherwise,
>> please try to see if the return values of these functions are
>> relevant to the well-being of your program.
>>
>> ~Robert Widmann
>>
>> 2016/10/30 8:49、Jody Schofield via swift-dev <swift-dev at swift.org>
>> のメッセージ:
>>> Sorry, I'm sure this has been discussed before, but what the heck???
>>>
>>> This feature is killing me. Now I have go add @discardableResult to
>>> every function that returns a non-Void or use the ugly syntax `_ =`?
>>>
>>> Until swift 3 I've really enjoyed the new language. Now I find it to
>>> be getting too rigid for the sake of "protecting" me from myself.
>>> The safety levels needs to be dialled back some.
>>>
>>>
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