I’m -1 on this feature. Default values is basically compile sugar for not
filling in the value at the call site. The protocol should clearly state
its purpose and not constrain its implementations with stuff like this.
I
disagree. According to the definition of
Protocol
<The Swift Programming Language: Redirect;
.
Protocol method declarations have the same form as function declarations,
with two exceptions: They don’t include a function body, and you can’t
provide any default parameter values as part of the function declaration.
The definition doesn't say we can't use default values in implementation.
The definition doesn't say we can't declare that a function must have or
have not default values. Only you can't set a default value in the protocol
function declaration.
This proposal is an improvement to the protocol and violate nothing.
zhaoxin
···
On Tue, Jan 19, 2016 at 12:53 AM, Sune Foldager <cyano@me.com> wrote:
I’m -1 on this feature. Default values is basically compile sugar for not
filling in the value at the call site. The protocol should clearly state
its purpose and not constrain its implementations with stuff like this.Also, the reason you’re getting “Good, Good” below is probably because
default parameters are a bit of a “last resort” in overload resolution.-Sune
On 16 Jan 2016, at 13:44, 肇鑫 via swift-evolution < > swift-evolution@swift.org> wrote:
Hi Haravikk,
I just implement a func like your examples. However, I find the result is
interesting.protocol Good {
func printSomething(something:String)
}extension Good {
func printSomething() { self.printSomething("Good") }
}struct Name:Good {
func printSomething(something: String = "John") {
print(something)
}
}struct Talk:Good {
func printSomething(something: String = "Hahaha") {
print(something)
}
}var protocols:[Good] = [Name(), Talk()]
for p in protocols {
p.printSomething() // Good, Good instead of John, Hahaha
}As you can see, the final result is "Good, Good", not as I expected "John,
Hahaha", is that right or is it a bug?zhaoxin
[…snip…]