Accessing functions by name (or something?)

[jwoertink]

Let's say I have a lua file like:

function one()
  print("one")
end

function two()
  print("two")
end

return one, two

Then I add these to the stack:

lua = Lua.load
code = lua.run File.new("./test.lua")

I can do a secondary run lua.run("one()"), but is there a way to gather these functions individually by a name or something?

What I'm looking to do is call them from within Crystal like one.as(Lua::Function).call. Then I can pass in args from Crystal. I know I can do this if I return a single function, but what if I return multiple functions, and I can't guarantee which order they were returned in?

[veelenga]

The get_global method on Lua::Stack lets you retrieve named functions individually:

  lua = Lua::Stack.new
  lua.run %q{
    function one()
      return "one"
    end

    function two()
      return "two"
    end
  }

  one = lua.get_global("one").as(Lua::Function)
  two = lua.get_global("two").as(Lua::Function)

  p one.call # => "one"
  p two.call # => "two"

  lua.close

When you define functions at the top level in Lua (without local), they become globals. You don't need to return them, just access them by name via get_global. If you prefer returning a table of named functions, that works too:

  lua = Lua::Stack.new
  fns = lua.run(%q{
    return {
      one = function() return "one" end,
      two = function() return "two" end
    }
  }).as(Lua::Table)

  p fns["one"].as(Lua::Function).call # => "one"
  p fns["two"].as(Lua::Function).call # => "two"

  lua.close