Re: C module and a Lua stub with the same name

[Ivan Kolev <ikolev@...>]

D Burgess wrote:
> > I guess if require passed as an argument to the Lua module the directory where it was found, then the Lua stub could easily load the .dll from the same directory.
>
> Well you are in luck.
>
> Try,
>
> table.foreach(debug.getregistry(),print)
>
> you will see stuff like
>
> LOADLIB: .\mypackage.dll userdata: 0032BC88
>
> This is the path where the package was found.

But this is done only when loading C modules. And I can't have the C module load the Lua implementation, because the default loading order is Lua->C - if I had MyLib.lua and MyLib.dll in the same directory, MyLib.lua would be loaded first :(

> > Is there a simple solution to this problem?
> Add you own loader to package.loaders or change the order
> of the loaders.

If I write a library intended for common use, I wouldn't want to mess with the default loading order.

It's a pity that I had to examine Lua's source to see that the filename of the loaded Lua module is stored as debug info of the module function... somehow I didn't think about debug.getinfo
This is what I do now in the beginning of MyLib.lua:

local function loadCmodule( modname, clibext, openFunc )
	local path = debug.getinfo( 2, "S" ).source
	modname = modname or string.gmatch( path,"([^\\/]+)\.lua$")()
	assert( modname, "Could not extract module name from path" )
	path = string.sub( path, 2, - #(modname .. ".lua") - 1 )
	clibext = clibext or ".dll"
	openFunc = openFunc or "luaopen_" .. modname
	modname = modname .. clibext
	local mod = package.loadlib( path .. modname, openFunc )
	mod = mod or package.loadlib( path .. "Release\\" .. modname, openFunc )
	mod = mod or package.loadlib( path .. "Debug\\" .. modname, openFunc )
	return assert( mod, "C module " .. modname .. " not found" )()
end

local cmod = loadCmodule()

... add Lua interface here

The above function loadCmodule() (or some improved version of it) seems like a good candidate for a common utils library.

I'd be interested to see how other libraries which have a Lua stub on top of a C module deal with this issue.

Regards,
Ivan