[Dev-luatex] Module searching

[Hans Hagen]

Heiko Oberdiek wrote:
> Hello,
> 
> in the TeX world scripts are usually installed below TDS:scripts.
> 
> Lua does know a module system.
> 
> Example: There is a package "foobar" with module "foobar.hello".
> Lua then searches in some standard places for
>   foobar/hello.lua
> 
> However LuaTeX neglects the texmf trees. Thus "package.loaders"
> could be extended by a kpse loader, e.g.:
> 
>   function kpse.module_loader(module) 
>     local file
>     if string.find(module, ".", 1, true) then
>       -- What to do?
>       -- the following is just an unreliable emergency workaround:
>       module = string.gsub(module, "^.*\%.", "")
>       file = kpse.find_file(module .. ".lua", "texmfscripts")
>     else
>       file = kpse.find_file(module .. ".lua", "texmfscripts")
>     end
>     if file then
>       local loader, error = loadfile(file)
>       if loader then
>         return loader
>       end
>       return "\n\t KPSE loading error:\n" .. error
>     end
>     return "\n\t KPSE search failed"
>   end
>   table.insert(package.loaders, kpse.module_loader) 
> 
> However, the problem are modules with dots.
> I haven't find a solution using kpse functions.
>   kpsewhich --format=texmfscripts foobar/hello.lua
> doesn't find the file.

well, maybe you could ask for the path variable, and loop over it

there's also luainputs

> Perhaps a search path could be hacked by using the output of
>   kpsewhich --show-path=texmfscripts
> and appending the module directories to each path component.
> But:
> * LuaTeX's kpse library doesn't have a "show_path" function.
> * os.execute is not available in safer mode.
> * Last but not least, a kpse function is missing for
>   searching along the modified path specification.

can't you use lua for that?

> * Portability among different operating systems.
>   (directory specificator, ..., LUA_DIRSEP isn't available, ...)
> 
> Ideas?

we explicitly didn't hard code these things because each user and/or 
macro package may want to do it different (the same for suffixes of lua 
files)

> Something like "foobar_hello.lua" isn't the best solution:
> * Redundancy in the full name:
>   TDS:scripts/foobar/foobar_hello.lua
> * It doesn't scale well, e.g. it pollutes "package.loaded".

Hans

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