You can write a helper method that adds a placeholder if the array is empty:
for name in names.placeholder("no names") {
print(name)
}
Implementation:
extension Collection {
func placeholder(_ elem: Iterator.Element) -> PlaceholderView<Self>
{
return PlaceholderView(collection: self, ifEmpty: elem)
}
}
enum PlaceholderView<C: Collection> : Collection {
case original(C)
case placeholder(C.Iterator.Element)
init(collection: C, ifEmpty: C.Iterator.Element) {
if (collection.isEmpty) {
self = .placeholder(ifEmpty)
} else {
self = .original(collection)
}
}
// implement Collection conformance
}
2017-02-01 19:48 GMT+03:00 Chris Davis via swift-evolution <
[email protected]>:
> Hi,
>
> Often when I’m programming I stumble upon this scenario:
>
> I have a list of items that may or may not be empty - if it’s full, I do
> one thing, if it’s empty I do something else, my code looks like this:
>
> class Example_1
> {
> let names = ["Chris", "John", "Jordan"]
>
>
> /// Loop over names, if no names, print no names
> func run()
> {
> for name in names
> {
> print(name)
> }
>
>
> if names.count == 0
> {
> print("no names")
> }
> }
> }
>
> let exampleOne = Example_1()
> exampleOne.run()
>
> However, Personally, I would find it more pleasing to write something like
> this:
>
> class Example_2_Proposed
> {
> let names:[String] = []
>
>
> /// Loop over names, if no names, print no names
> func run()
> {
> for name in names
> {
> print(name)
> } else {
> print("no names")
> }
> }
> }
>
> let exampleTwo = Example_2_Proposed()
> exampleTwo.run()
>
> The difference here is a “for-else” type syntax where if there were no
> items in the array it would simply fall through to the else statement.
>
> What would be the pros/cons of introducing such syntax?
>
> Is there’s a way of doing something similar in swift already?
>
> Thanks
>
> Chris
>
>
>
>
>
> _______________________________________________
> swift-evolution mailing list
> [email protected]
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
>
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