11 replies to this topic

[Calimore]

How can I call a function from a string...?

I have found this example but this doesn't work for me... What's wrong?

function foofunc ()
  print ("foo")
end

x='foofunc'

_G[x]()

I'm getting "attempt to call nil" for _G[x]()

[Bomb Bloke]

function foofunc ()
  print ("foo")
end

x = loadstring("foofunc()")
x()

-- Or just:

loadstring("foofunc()")()

[Engineer]

 Bomb Bloke, on 26 May 2013 - 07:46 AM, said:

function foofunc ()
  print ("foo")
end

x = loadstring("foofunc()")
x()

-- Or just:

loadstring("foofunc()")()

Im going to disagree on this one. Loadstring should be only used when it cant be done else.
I would suggest this, since you want to load if globally:

function _G['foobar']()
  print("foo")
end

_G["foobar"]()

You actually dont need to load it in the global table:

local functions = {}
function functions['foobar']()
   print("foobar")
end

local x = 'foobar'
functions[x]()

[Calimore]

Thank you both for the insight into how this could work...

I'll play around with this a little bit.

[Calimore]

 Engineer, on 26 May 2013 - 07:57 AM, said:

local functions = {}
function functions['foobar']()
  print("foobar")
end

local x = 'foobar'
functions[x]()

Unfortunately this does not work... Error is: '(' expected in line 2

[theoriginalbit]

 Calimore, on 26 May 2013 - 11:52 AM, said:

Unfortunately this does not work... Error is: '(' expected in line 2

Yeh you need to do one of these two

functions['foobar'] = function()
  print("foobar")
end

or this

function functions.foobar()
  print("foobar")
end

[Calimore]

 theoriginalbit, on 26 May 2013 - 11:55 AM, said:

 Calimore, on 26 May 2013 - 11:52 AM, said:

Unfortunately this does not work... Error is: '(' expected in line 2

Yeh you need to do one of these two

functions['foobar'] = function()
  print("foobar")
end

or this

function functions.foobar()
  print("foobar")
end

Ahh... much better! This is it...

Thanks a lot

[theoriginalbit]

 Calimore, on 26 May 2013 - 12:01 PM, said:

Ahh... much better! This is it...

Thanks a lot

No problems. Oh I should mention if you want a key with a space in it, you will need to use the first method.

This is ok

functions["some name"] = function()
  print("foo")
end

This is not ok

function functions.other name()
  print("bar")
end

[Calimore]

 theoriginalbit, on 26 May 2013 - 12:05 PM, said:

Oh I should mention if you want a key with a space in it, you will need to use the first method.

I suspect the same goes for numbers. I was having problems with that...

[Engineer]

 Calimore, on 26 May 2013 - 02:28 PM, said:

I suspect the same goes for numbers. I was having problems with that...

Yes, but for numbers you dont use quotes:

local t = {}
local t[1] = function()
   print("I'm index 1!")
end

[Calimore]

Thanks again... Much appreciated!

Most of what i'm doing is trying to figure out how LUA works. What I try to do is provide myself with some sort of unified computer-to-computer messaging protocol.
All messages I transmit should share a common header and a variable body. The message header contains basic stuff as senderID, receipientID as well as a messageID which I then use to call a function that deals with it's actual message body itself.

By using this way of function calling I can introduce new functions into the code without having to touch any other line of code. Do you think this is overly complicated...? I simply didn't want to do a giant "ifelse" statement... Are there any drawbacks doing it this way...?

[Hawk777]

If you really, really want to access a function defined in the current file by name with no special syntax used at point of definition, what about this?

function myfunc()
  print("Hello World")
end

fname = "myfunc"

getfenv()[fname]()

The above snippet outputs the string “Hello World”.