> On Aug 18, 2016, at 10:56 AM, Davor Jankolija <[email protected]> wrote:
>> On 18 Aug 2016, at 19:46, John McCall <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>>> On Aug 18, 2016, at 10:15 AM, Davor Jankolija via swift-evolution
>>> <[email protected] <mailto:[email protected]>> wrote:
>>>
>>>> This is a warning right now — do you think it should be an error?
>>>>
>>>> Slavas-MacBook-Pro:~ slava$ cat ttt.swift
>>>> func f() {}
>>>>
>>>> func g() {
>>>> try f()
>>>> try? f()
>>>> }
>>>>
>>>> Slavas-MacBook-Pro:~ slava$ swiftc ttt.swift
>>>> ttt.swift:4:3: warning: no calls to throwing functions occur within 'try'
>>>> expression
>>>> try f()
>>>> ^
>>>> ttt.swift:5:8: warning: no calls to throwing functions occur within 'try'
>>>> expression
>>>> try? f()
>>>> ^
>>>
>>> IMHO at least, this should be an error. As a side note I do think that try
>>> should have greater precedence than as, even though this does potentially
>>> limit calls that would use only one try on a series of throwing statement
>>> that can be handled using parentheses. The benefit is that try is probably
>>> called in the vast majority of situations (that’s my experience at least)
>>> on a single throw statement and having it have higher precedance would
>>> avoid some surprises as most developers probably already assume that try
>>> wil be executed before as.
>>
>> The design of ordinary 'try' and 'try!' are that they includes the entire
>> expression to the right, spanning casts and other binary operators, and I
>> think that's clearly the right rule for them. It's not as clearly right for
>> 'try?', but making 'try' and 'try?' be parsed differently would be horribly
>> confusing.
>>
>> John.
>
> I see what you’re saying and I have to agree for the most part, it’s just
> that now you basically get a ‘try’ executed on the result of the ‘as?’
> expression, which although is correct now that I look at your explanation is
> somewhat unintuitive, again this is just my opinion.
>
> P.S.
> It would seem then, that the best way and probably simplest is to remember
> and place parentheses around the ‘try call()’ and then attempt a cast?
In your case, yes, I think the right solution is probably to parenthesize the
try?.
John.
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