Re: Load Compiled Script?

["Jim Jones" <jjones@...>]

I think you're right on this one.  It does make better sense to allow them
to make definitions outside the scope of their event functions.

I certainly appreciate everyone's input and Wim's hardwork coding. Thanks
guys.

Jim

----- Original Message -----
From: <RLake@oxfam.org.uk>
To: "Multiple recipients of list" <lua-l@tecgraf.puc-rio.br>
Sent: Wednesday, April 30, 2003 10:27 AM
Subject: Re: Load Compiled Script?


>
> Jim Jones escribió:
>
> -- I want to make definitions, such as the following,
> -- illegal within my system;
> -- All code needs to be contained within function definitions.
> x = 5
>
>
> Why make it illegal? It seems to me to make perfect sense.
>
> If I were scripting in your system, I might well want to throw
> some definitions into the beginning of the script file which
> could be used by my functions. In fact, the power of Lua as
> a configuration language derives exactly from the ability of
> the configurer to execute and not just write configuration files.
>
> The key is that you don't want those definitions to pollute
> the global environment in which your system is running, and
> furthermore you want certain globals to be visible to the
> script files (along with the globals defined in the script
> file). So you need to load and execute the script within
> a specific environment. In Lua 5, I think (Wim will no doubt
> correct me if this isn't right: I'm in a slightly different
> mindset with respect to global environments) you should be
> able to do this as follows:
>
> their_definitions = loadfile "somefile.lua"
> their_env = {
>   math = math, -- give them the math library
>   _STATVERSION = "2.3", -- tell them which version they're in
>   -- etc.
> }
>
> -- Note: rather than adding math as a table to the scripting
> -- environment you present, you might want to give them the
> -- functions as (apparent) globals. But you don't want to
> -- copy raw functions into their environment or the for
> -- statement (below) will fail. So use an __index metamethod
> -- instead: this could easily be generalised to handle more
> -- than one library package:
>
> setmetatable(their_env, {__index = math})
> -- or
> setmetatable(their_env, {
>   __index = function(t, k)
>   return my_utils[k] or math[k] or table[k] or string[k]
> })
>
> setfenv(their_definitions, their_env)
>
> their_definitions() -- now run their script.
>
> for k, v in their_env do
>   if type(v) == "function" then
>     add_to_function_menu(k)
>   end
> end
>
> -- could be generalised to take arguments and return results
> function run_their(function)
>   their_env[function]()
> end
>
> -- ...
>
> run_their "initialise"
> -- do some statistics
> run_their(menu_config.summary_function)
>
> -- etc.
>
>
>
>