[swift-evolution] [Idea] if let value!

[Daniel Höpfl]

That's the idea of "let?".
"let!" would always execute the block (and crash if the optional is 
nil.)

"if let!" is meaningless: "let!" would be true (if the optional is set) 
or crash (if the optional is nil).

On 2016-05-18 14:27, Vladimir.S wrote:
> The idea to process the 'if' block only if anOptional is not null
> 
> In case of
> let! anOptional {
> }
> IMO it is not clear that this block will be executed *only* if
> anOptional is not null.
> 
> if let! anOptional {
>  // here only if anOptional != null
> }
> - seems like similar to standard 'if let' construction so should not
> confuse too much and IMO will be remembered after the first
> appearance/using.
> 
> On 18.05.2016 15:15, Daniel Höpfl via swift-evolution wrote:
>> Would it be possible to drop the "if"? I don't see why we need it.
>> 
>> On 2016-05-18 11:22, LM wrote:
>>> I am experimenting with this:
>>> 
>>> If var! anOptional {
>>>    anOptional   // unwrapped, shadowing
>>> }
>>> 
>>> if let! anOptional {
>>> ... // same
>>> }
>>> 
>>> 
>>> This compiler codebase is truly remarkable, so it should also works 
>>> with
>>> 
>>> If var! opt1 where opt1 < 27 {
>>> }
>>> 
>>> or
>>> 
>>> if var! opt1, opt2 {
>>>    // both unwrapped
>>> }
>>> 
>>> LM/
>>> 
>>> 
>>>> On May 18, 2016, at 10:21 AM, Daniel Höpfl via swift-evolution
>>>> <swift-evolution at swift.org> wrote:
>>>> 
>>>> Just an idea: Why don’t we think about it similar to try?
>>>> 
>>>> var anOptional : String?
>>>> 
>>>> let? anOptional { /* use it, but cannot change it */ }
>>>> let! anOptional { /* use it, without checking, cannot change it */ }
>>>> 
>>>> var? anOptional { /* use it, can also change it, */ }
>>>> var! anOptional { /* use it, without checking, can also change it */ 
>>>> }
>>>> 
>>>> Is it allowed to set it to nil in the var case? Hard to say.
>>>> 
>>>>> On 17.05.16 15:43, Vladimir.S via swift-evolution wrote:
>>>>> It is common to shadow optional value name with unwrapped value 
>>>>> with
>>>>> same name:
>>>>> 
>>>>> if let someGoodValue = someGoodValue {...}
>>>>> 
>>>>> What if we'll have a syntax to not repeat the variable name to 
>>>>> achieve
>>>>> the same target:
>>>>> 
>>>>> if let someGoodValue! {...}
>>>>> 
>>>>> What do you think?
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