DIP 1019--Named Arguments Lite--Community Review Round 1

[Paul Backus]

On Friday, 15 February 2019 at 12:56:45 UTC, Mike Parker wrote:
> This is the feedback thread for the first round of Community 
> Review for DIP 1019, "Named Arguments Lite":

The fact that named arguments, as proposed, require both the 
caller *and* the callee to opt-in seems like it would make them 
almost useless in practice. Even if someone's willing to put in 
the effort of going through all of Phobos to figure out which 
functions should be annotated with @named, that still leaves all 
of the packages on code.dlang.org to deal with. Realistically, a 
lot of existing code will never be updated to work with this 
feature, even if it could benefit from it.

It's also a pretty unsightly wart for newcomers to D to first 
learn that D supports named arguments (hooray!), and then find 
out that no, they can't use them with <insert package here> 
(boo!), because the author of that package hasn't "said the magic 
word" to enable them.

I understand that the intent is to avoid unintentional breakage, 
but this feature is already opt-in from the caller's side. If 
someone wants to write code that's robust against parameter name 
changes, they can do it by not using named arguments in the first 
place. And, as noted in the DIP itself, there are still 
opportunities for accidental breakage even with @named, when the 
caller fails to re-compile their code after a parameter name 
change.

Parameter lock-in is definitely a legitimate concern, but IMHO 
adding a neutered version of named arguments like this one to the 
language would be worse than not having named arguments at all.