On Tuesday, 3 September 2013 at 19:30:53 UTC, Walter Bright wrote:
On 9/3/2013 9:00 AM, Piotr Szturmaj wrote:
How about specifying extern(C) before each C structure? The
majority of bindings
already have "extern(C):" on top of module.
While we could do that, at what point does this become arcane
complexity?
I think it depends how much metaprogramming could benefit in the
language. Algebraic datatypes use zero sized structs in may
places (see Rust, with Option(T) variants None and Some(T)), and
I've heard of devs using structs as namespaces. In C, there was
pretty much no metaprogramming to speak of, so semantic struct
sizes just weren't a bit deal (as far as I can tell, that is).
But, in D, metaprogramming is a ubiquitous feature, so I do think
it's reasonable to consider some way of specifying zero sized
structs in the language. I'd argue for it to be an opt-in feature
though, so empty structs, by default, can't have a zero size.
This keeps code backwards compatible.
Perhaps something like `enum struct Foo;`, to indicate that it's
just a compile-time used distinct type, and not a value? Just
throwing that out there. I'm sure there is a better way to
indicate that a type is just used as a type/namespace, without a
value persay.
When you say retain C compatibility, do you mean having C code
which makes use of empty structs still be compile-able with the D
compiler? Or D code inter-oping with external C libraries?
