https://issues.dlang.org/show_bug.cgi?id=17953
Bastiaan Veelo <basti...@veelo.net> changed:
What |Removed |Added
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CC| |basti...@veelo.net
--- Comment #2 from Bastiaan Veelo <basti...@veelo.net> ---
This came up again at the DLF quarterly meeting April 5, 2024, with industry
partners, and Walter asked to make sure there is a feature request. As
discussed there:
For arguments and return types of various mutability we have the `inout`
keyword that saves us from having to define multiple function overloads[1]. A
similar solution for other attributes does not exist.
For example, if you have foreach loops over a struct S both in a @nogc context
and with an allocating loop body,
```d
void f()
{
S s;
foreach (a; s)
allocating(a);
}
void g() @nogc
{
S s;
foreach (a; s)
nonallocating(a);
}
void allocating(int) {}
void nonallocating(int) @nogc {}
```
then S needs both of these opApply overloads:
```d
int opApply(scope int delegate(int) dg);
int opApply(scope int delegate(int) @nogc dg) @nogc;
```
Similar for @safe, nothrow, pure and their permutations.
Templating opApply[2] can help in many of these cases, but problems arise when
classes and inheritance get involved[3].
There is a DIP for argument dependent attributes[4] but work on it has stalled.
[1] https://dlang.org/spec/const3.html#inout
[2] https://dlang.org/spec/statement.html#template-op-apply
[3] https://youtu.be/9lOtOtiwXY4?si=KME_ZddnrecMdWOJ&t=359
[4] https://github.com/dlang/DIPs/pull/198
--
