enum: Replacing current type conversion by enums

[farodin91]

Fixes #7
@sahid What do you think?

[sahid]

Hum.. I'm not totally convinced by this, is there any document or example which are using such practice for ffi?

[sahid]

With your change it will be still possible to document the fields? something like:

virt_enum! {
  ConnectCredentialType {
    /// Requests username blabla....
    Username -> 1,
    ...
}

[farodin91]

I need to change something, using meta attr.

[farodin91]

I didn't find a good example. You can use enums easly in match. For me it looks better. I'm also not finished.

[farodin91]

This version force comments, but only support a single command. The reason is a bug in rust rust-lang/rust#24827.

[sahid]

It's a very nice work but I dont think we should use a macro. We don't have so much constants to convert so we should implement them correctly using an enum.

Then about to do the conversion I'm thinkin about using Procedural Macros so perhaps at the end to have something like:

#[Derive(ConvertToC)]
pub enum Something {
  Value1 = 1,
  Value2 = 2,
  ...
}

Also it's very nice to have started documenting the fields, if you really want do that, the best is to reuse what we have in the header of libvirt, like: http://libvirt.org/git/?p=libvirt.git;a=blob;f=include/libvirt/libvirt-domain.h;h=45f939a8cc37e8e29bea13316a222338b53774fe;hb=HEAD#l291

Also a last question what about to keep the name in uppercase?

#[Derive(ConvertToC)]
pub enum Something {
  VALUE1 = 1,
  VALUE1 = 2,
  ...
}

[farodin91]

This should also work.

#[repr(C)]
pub enum Test {
  Value = 1
}

[sahid]

This is how I would see the thing:

https://github.com/sahid/libvirt-rs/blob/poc/enum/src/error.rs#L45

What do you think?

[farodin91]

This would be great.

[farodin91]

Combined solution would be wrapping these into an macro to auto create From traits until derive is implemented.

impl_enum!{
  #[derive(Debug, PartialEq)]
  pub enum ErrorLevel {
    /// No error
    None = 0,
    /// A simple warning.
    Warning = 1,
    /// An error.
    Error = 2,
  }
}

Normally enums in Rust are CamelCase.

[farodin91]

https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md#enums

[sahid]

My thinking is we should do it by procedural macro and so use derive or we should do it by hands (it's not all the constants that needs to be converted from).

[sahid]

@farodin91 please let me know if you still want to continue to work on this issue, if not I could take the lead :)

Thanks

[farodin91]

You could take it.