On 10.06.2017 7:07, Justin Oroz via swift-evolution wrote:
First time trying to contribute, hopefully this is the proper channel to submit.
I propose an addition to the guard let statement to allow for replacement of
optionals with unwrapped values.
ex)
two current options
obj.methodWithCallback() {(foo, bar) in
guard let foo = foo else {
return
}
foo.prop = “new”
}
OR
obj.methodWithCallback() {(foo, bar) in
guard foo != nil else {
return
}
foo!.prop = “new”
}
I propose the following option:
obj.methodWithCallback() {(foo, bar) in
guard foo else {
return
}
foo.prop = “new”
}
This reduces the seemingly redundant "guard let foo = foo” statement and
removes the unnecessary forced optional unwrapping.
There was a discussion about similar subject in the list and was decided IIRC that
shadowing is not a good practice so it doesn't worth a special syntactic sugar.
(correct me if I'm missing something)
Personally, I believe shadowing already (and will be) used very often(usually because
we already have a good name for variable, and it is hard to invent one more) and
*good* syntactic sugar for it will make Swift code more clean. But I like the
suggestion with 'let' keyword for such shadowing to make it clear that 'foo' is
shadowed(re-declared) with its unwrapped version :
obj.methodWithCallback() {(someMeaningfulName, bar) in
guard let someMeaningfulName else {
return
}
someMeaningfulName.prop = “new”
}
Note that if it's 'foo' - it seems not a problem to write
guard let foo = foo else {..},
but when we have
guard let someMeaningfulName = someMeaningfulName else {..}
, we have to parse each variable to check if the same name declared or probably
different name. Plus DRY principle.
if let someMeaningfulName {
// unwrapped someMeaningfulName here
}
instead of
if let someMeaningfulName = someMeaningfulName {
}
- Justin
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