Reader/Writer/Rewindable interfaces

[ruby]

Reader/Writer/Rewindable interfaces

[marcandre]

I agree, it looks like the sig for IO is incomplete. _Reader, _Writer, _Rewindable should probably be IO::_Read, IO::_Write and IO::_Rewind. _ToIO should be global; if it is much used, maybe io (like string vs String) could be used?

[marcandre]

PS: there is already a _Writeable interface.

[HoneyryderChuck]

I would probably not make it rely on the IO names pace, as buffer type structures such as StringIO or Tempfile aren't IOs, however these interfaces can be applied to it.

[soutaro]

Thank you for pointing out the bad types of IO methods. (Would you mind opening a PR to fix them?)

Technically it's unnecessary to define a set of common interfaces beforehand, while I know it would be useful. Because the relationship between interfaces and classes/modules are detected implicitly, without any declaration, having API specific and possibly duplicated interfaces works fine.

So, the steps I assume are:

1. Define local interfaces for IO methods.
2. Use the interface in IO method definitions.
3. Promote it if we find they are useful for other methods too.