LTR Romtables don't support __call metamethod

[drauschenbach]

Use of LTR __metatable docs are thin, and I'm doing my best to work from the source code.

First, I'm surprised that the metatable map returned is always self, rather than the one I'm pointing at via an LRO_ROVAL.

Given:

const LUA_REG_TYPE mymodule_metatable_map[] = {
  { LSTRKEY("__call")  , LFUNCVAL(myCallMetamethodHandler) },
  { LNILKEY, LNILVAL }
};

const LUA_REG_TYPE mymodule_map[] = {
  { LSTRKEY("__metatable"), LRO_ROVAL(mymodule_metatable_map) },
  { LNILKEY, LNILVAL }
};

It seems to ignore the metatable and registers a metatable of self:

m = require 'mymodule'
print(m)
romtable: 0x805c9b8

for k,v in pairs(m) do print(k,v) end
__metatable     romtable: 0x805c9b8

print(getmetatable(m))
romtable: 0x805c9b8

for k,v in pairs(m) do print(k,v) end
__metatable     romtable: 0x805c9b8

So given that, I went back to a single consolidated romtable that uses itself as a metatable:

const LUA_REG_TYPE mymodule_map[] = {
  { LSTRKEY("__call") , LFUNCVAL (myCallMetamethodHandler) },
  { LSTRKEY("__metatable"), LRO_ROVAL(mymodule_map) },
  { LNILKEY, LNILVAL }
};

And __call seems to get ignored:

> m('foo')
stdin:1: attempt to call global 'm' (a romtable value)

[drauschenbach]

I'm basically looking for a way to register the url.parse module, which returns a function rather than a table. Other popular modules do that as well, which is why I'm looking for the generalized solution. I've filed an independent issue #144.