Comment #0 by qs.il.paperinik — 2023-06-21T09:12:25Z
UFCS makes it possible to call a non-member function as if it were a member function of the first parameter’s type. The reverse is not true, however. A member function cannot be called as if it were a non-member function that takes the aggregate type that contains it as the first parameter explicitly:
```d
struct S
{
void mem() {}
}
void nonmem(S) {}
void main()
{
S s;
s.mem(); // ok
mem(s); // fails
s.nonmem(); // ok (UFCS)
nonmem(s); // ok
}
```
I suggest to make the non-member call syntax universal as well. The same as preferring the member function in member function syntax over an eponymous non-member function in scope, we prefer the non-member function in the non-member function call syntax over an eponymous member function of the type of the first argument.
This, plus https://issues.dlang.org/show_bug.cgi?id=24004, would make it unnecessary to remember if a functionality is provided via a non-member or member function in quite a lot of cases.
A bit of nomenclature:
UNFCS: Universal non-member function call syntax. The (new) mechanic that `mem(obj)` works because `obj` has a member `mem`.
UMFCS: Universal member function call syntax: The (already present) mechanic that `obj.nonmem` works because a non-member function takes `typeof(obj)` as its first parameter.
UFCS: Umbrella term for both UNFCS and UMFCS.
Comment #1 by robert.schadek — 2024-12-13T19:29:49Z