Is it possible to find out how many named arguments does a function expect?

Question

In JavaScript, you can ask a function object how many arguments does it expect. Is the same thing possible in Lua?

For a function implemented in Lua, you can also get a "signature" of sorts. See my [answer](http://stackoverflow.com/a/24216007/2226988) to [Is there a way to determine the signature of a Lua function?](http://stackoverflow.com/q/142417/2226988). — Tom Blodget, Jul 10 '14 at 02:39

Mud · Accepted Answer · 2014-07-09T21:22:47.210

4

If you're using Lua 5.2, you can use debug.getinfo(f).nparams.

(answer edited in light of Luiz's answer, previous answer was correct only for Lua 5.1)

edited Jul 09 '14 at 21:22

answered Jul 09 '14 at 17:46

Mud

You should also add that __ANY__ number of arguments can be passed to a function in lua. – hjpotter92 Jul 09 '14 at 18:05

lhf · Answer 2 · 2014-07-09T21:04:10.347

2

You can do it using the debug library:

print(debug.getinfo(f).nparams)

edited Jul 09 '14 at 21:04

answered Jul 09 '14 at 20:49

lhf

2 Answers2