> let john = {firstName="John"; lastName="Doe"}
> let alice = {john with FirstName="Alice"}
>
> Current way to do this in Swift is:
>
> let john = (firstName:"John", lastName:"Doe")
> var alice = john
> alice.firstName = "Alice"
I think this is better modeled in Swift as something like:
let john = (firstName:"John", lastName:"Doe")
let alice = with(john) {
$0.firstName = "Alice"
}
`with` would be something like:
func with<Value>(value: Value, function: Value throws -> Void) rethrows
-> Value {
var mutableValue = value
return try function(&mutableValue)
}
This would serve many different purposes:
* If the value is a value type, allows you to return a modified copy
* Allows you to customize a value's properties immediately after initializing
it, which many people have asked for
* Acts as a `tap` function when the block doesn't change the value (see
<http://ruby-doc.org/core-2.3.0/Object.html#method-i-tap>)
--
Brent Royal-Gordon
Architechies
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