On Thursday, 17 September 2020 at 12:58:06 UTC, Mike Parker wrote:
DIP 1030, "Named Arguments", has been accepted.
During the assessment, Walter and Atila had a discussion
regarding this particular criticism:
https://forum.dlang.org/post/[email protected]
"Named arguments breaks this very important pattern:
auto wrapper(alias origFun)(Parameters!origFun args)
{
// special sauce
return origFun(args);
}"
They say that, though it's true that `Parameters!func` will not
work in a wrapper, it "doesn't really work now"---default
arguments and storage classes must be accounted for. This can
be done with string mixins, or using a technique referred to by
Jean-Louis Leroy as "refraction", both of which are clumsy.
So they decided that a new `std.traits` template and a
corresponding `__traits` option are needed which expand into
the exact function signature of another function.
They also acknowledge that when an API's parameter names
change, code depending on the old parameter names will break.
Struct literals have the same problem and no one complains (the
same is true for C99). And in any case, when such a change
occurs, it's a hard failure as any code using named arguments
with the old parameter names will fail to compile, making it
easy to see how to resolve the issue. Given this, they find the
benefits of the feature outweigh the potential for such
breakage.
Very practical features, similar to trailing closures, are
expected.
