C Binding Generation: Request for Comments

[Ori Bernstein <ori@xxxxxxxxxxxxxx>]

So, I'm looking at improving mcbind and making it usable in general for
defining Myrddin modules.

Current State
-------------

    At the moment, it transitively includes *everything*. This means that if you
    generated bindings for sqlite.h and for xcb/xcb.h, you would get common types
    duplicated, leading to, for example, sqlite.size_t and xcb.size_t.

Sketch of Proposal
------------------

    To solve this, I've been eying giving mcbind knowledge of modules and module
    interdependencies. The way this would work:
    
      - First, we parse the module file, which contains a list
        of files to include, and a list of modules that it depends
        on.
      
      - For each module, we recursively load it, and read the declarations,
        putting them into that module's namespace.
      
      - Then, we load each of the headers defined in the module, from
        scratch. If we've already seen a declaration in a previous module,
        it is discarded.
      	
      - Finally, the code is emitted. Only the module that has been passed
        directly is processed. Any recursively loaded modules are omitted.
      
    This also allows for recording which cflags and ldflags should be used,
    in the module definition.
	
Module Definitions
------------------

    Borrowing quite a few ideas from the C++ modules discussion, I'm thinking
    that I might define something like this:

        pkg stdlibc =
	    header = "stdint.h"
	    header = "stdio.h"
	    header = "stddef.h"
	    ...etc...
	    ldflags = -lc
	;;

	pkg x11 =
	    use stdlibc
	    header = "X11/X.h"
	    header = "X11/Xproto.h"
	    ...etc...
	    ldflags = -lX11
	    cflags = -Dwhatever
	;;

    This has at least two major problems:
    
    	1) Portability. system C headers are disgusting, confusing, and almost
	   as bad as the tools like autoconf that spawned to deal with them.
	   Required linker flags re different between platforms. There are
	   tons of different discovery systems.

	2) Fragility. For example, if one of the dependencies is missing an
           include, then symbols will be dumped into the wrong place.

Comments, thoughts, insults?

-- 
    Ori Bernstein