impl Debug for NifTerm

[jorendorff]

impl Debug for NifTerm

[jorendorff]

erlang_nif-sys doesn't expose enif_snprintf because it takes a variable number of arguments. However, I hacked this into erlang_nif-sys/lib.rs and it worked:

extern "C" {
    pub fn enif_snprintf(str: *mut c_char, size: size_t, format: *const c_char, term: ERL_NIF_TERM) -> c_int;
}

I think enif_snprintf is new in Erlang/OTP 19, which maybe means we should put it behind a feature flag. Everything else works in Erlang/OTP 18 and up.

[jorendorff]

See 7ca1e09.

[scrogson]

Could this be something we could only make available when using in debug mode? If you attempt to use in release mode it would not compile?

[hansihe]

No, the debug trait simply describes what happens when you try to debug print something. I don't think there is any reason this should only be available in release mode.

[scrogson]

@hansihe I think you misunderstood me? I was saying that the Debug trait impl should only be available if the crate is compiled in debug (default) mode. If the crate is compiled in release mode, any debug formatting left in could throw a compile error.

I'm not even sure this is possible or a good idea, just throwing it out there.

But also putting it behind a feature could be a nice way to make it optional.

[hansihe]

Seeing as no other debug implementations do this, I don't think we should do it either.

[jorendorff]

I just found out that Rust does support varargs for extern "C" functions. So this will be pretty easy, it starts with uncommenting a few lines in erlang_nif-sys.

[jorendorff]

rusterlium/erlang_nif-sys#23

[hansihe]

This was resolved a while ago.