Use lua to manipulate functions

bar-premake-use.lua

LIBS = {}
DEPS = {}


EXPORTS = {'bar'}

bar = {}
function bar.use_nonpopular_bar()
    print 'bar.use_nonpopular_bar'
end

foo-premake-use.lua

LIBS = {}
DEPS = {}


EXPORTS = {'foo'}

foo = {}
function foo.use_nonpopular_foo()
    print 'foo.use_nonpopular_foo'
end

foo2-premake-use.lua

LIBS = {}
DEPS = {}


EXPORTS = {'foo'}

foo = {}
function foo.use_nonpopular_foo()
    print 'foo.use_nonpopular_foo-2'
end

function foo.use_nonpopular_foo2()
    print 'foo.use_nonpopular_foo2'
end

framework.lua

 -- load data from file into a separated namespace
local function loaddata(file, setup)
    local f,e = loadfile(file)
    if not f then error(e, 2) end

    -- Create the namespace.
    local ns = setmetatable({}, {__index=_G})

    setfenv(f, ns)
    f()

    return ns
end


-- load foo
local nsfoo = loaddata('foo-premake-use.lua')
local exported_name_foo = nsfoo.EXPORTS[1]
print(exported_name_foo)

local exportednsfoo = nsfoo[exported_name_foo]
exportednsfoo.use_nonpopular_foo()


-- bring to global namespace
_G[exported_name_foo] = exportednsfoo
foo.use_nonpopular_foo()


-- load bar
local nsbar = loaddata('bar-premake-use.lua')
local exported_name_bar = nsbar.EXPORTS[1]
print(exported_name_bar)

local exportednsbar = nsbar[exported_name_bar]
exportednsbar.use_nonpopular_bar()

-- bring to global namespace
_G[exported_name_bar] = exportednsbar
bar.use_nonpopular_bar()



-- load foo2 - handle name clashes
local nsfoo2 = loaddata('foo2-premake-use.lua')
local exported_name_foo2 = nsfoo2.EXPORTS[1]
print(exported_name_foo2)

local exportednsfoo2 = nsfoo2[exported_name_foo2]
exportednsfoo2.use_nonpopular_foo()
exportednsfoo2.use_nonpopular_foo2()

-- merge
if _G[exported_name_foo2] then
   local t = _G[exported_name_foo2]
   for k, v in pairs(exportednsfoo2) do
       if t[k] then
           -- function conflicts detected
           print(k .. ' already exists in table ' .. exported_name_foo2)
       else
           t[k] = v
       end
   end
end

-- now foo is brought into the global namespace from premake_use.lua, and get merged from different files
foo.use_nonpopular_foo()
foo.use_nonpopular_foo2()