List Lua functions in a file

Question

How can I list all the functions included in a Lua source file?

For example, I have fn.lua which contains

function test1()
        print("Test 1")
end

function test2()
        print("Test 2")
end

And I wish to be able to display those function names (test1, test2) from another Lua script.

The only way I can figure at the moment is to include the file using require, then list the functions in _G - but that will include all the standard Lua functions as well.

Of course I could just parse the file manually using the string search functions, but that doesn't seem very Lua to me!

This will eventually form part of a process that allows the developer to write functions in Lua, and the operator to select which of those functions are called from a list in Excel (yuk!).

Answer 1

If you put them all in a "module" (which you should probably do, anyway):

mymodule = { }
function mymodule.test1()
    print("Test 1")
end

function module.test2()
    print("Test 2")
end

return mymodule

It becomes trivial:

mymodule = require"mymodule"

for fname,obj in pairs(mymodule) do
    if type(obj) == "function" then
        print(fname)
    end
end

If you absolutely have to keep them in raw form, you'd have to load them in a different way to separate your global environment, and then iterate over it in a similar way (over the inner env's cleaned _G , perhaps).

Answer 2

I see three ways:

1. Save the names in _G before loading your script and compare to the names left in _G after loading it. I've seen some code for this, either in the Lua mailing list or in the wiki, but I can't find a link right now.

2. Report the globals used in a function by parsing luac listings, as in http://lua-users.org/lists/lua-l/2012-12/msg00397.html .

3. Use my bytecode inspector lbci from within Lua, which contains an example that reports globals.

Answer 3

If you want to do this, it's better to define the function is a package, as described in Programming in Lua book :

functions = {}
function functions.test1() print('foo') end
function functions.test2() print('bar') end
return functions

Then you can simply iterate your table functions .