Discussion Thread: DIP 1030--Named Arguments--Final Review

[Steven Schveighoffer]

On 5/12/20 8:37 PM, Walter Bright wrote:
> We already have named arguments in D since the very beginning - the 
> struct initialization syntax.
> 
> Not a single person has complained about breakage when implementers 
> changed the names of the struct fields.

As was pointed out in the last review -- if you have structs with public 
member fields and you changed those names, the breakage would be more 
severe than just a broken initializer call:

auto s = S(1, 2, 3);

writeln(s.foo); // Error, no member foo, did you mean Foo?

It's weird to expect anyone to complain about initializer calls over 
actual usage.

> This is similar to:
> 
> 1. what happens if the implementer changes the types of the parameters?
> 
> 2. what happens if the implementer changes the order of the parameters?
> 
> Then user code breaks.
> 
> If anything, this feature will motivate implementers to take some care 
> to name the parameters appropriately.

I agree, and I don't think this is going to make a huge problem for D. 
It would, however, be nice to provide a way to migrate parameter names 
like we have for functions (via deprecation attributes).

-Steve