On 07/08/2017 08:17 AM, Andrei Alexandrescu wrote:
On 7/8/17 6:15 AM, Walter Bright wrote:
Has anyone a better idea? Does anyone want to write a DIP for this?
An attribute is fine. A more PL-minded possibility is to return a
specific type:
struct None
{
@disable this();
@disable this(this);
@disable @property None init();
}
None ThisFunctionExits();
The compiler detects (without having anything hardwired about the
particular type "None") that the type None is impossible to create and
copy/move from a function, and therefore decrees the function will never
return.
Pro:
- Having the indication "this doesn't return" syntactically be the
return type makes a lot of sense. I like that a lot. (Though I'd have no
objection to Walter's original suggestion either).
- It's one less built-in @attribute to scare people away with objections
of "too many attributes"! (And admittedly, idiomatic D can end up with
lots of attribtes all over the place.)
Con:
- Inferring that a type is meant to indicate "functions 'returning' this
do not return", strikes me as very round-about, hackish, unintuitive and
just unclean.
I really think this is one case where a dedicated compiler-understood
symbol is not only fully justified but also much cleaner.
That would be my #1 top preference: Your suggestion here, but just make
"NoReturn" (or whatever it'll be called) a special compiler-understood
"type", not something inferred from the detailed of a library-provided type.
In any case, I'm definitely onboard with the idea of having SOME
standard way to tell the compiler "this does not return". That would be
nice to have.
