Authors CurseForge

local someStringToRuleThemAll = "arg3 arg1"

local function test(arg1, arg2, arg3)
	if someStringToRuleThemAll == "arg3 arg1" then
		print(arg3, arg1)
	elseif someStringToRuleThemAll == "arg1 arg3 arg2" then
		print(arg1, arg3, arg2)
	end
end

• Approach 1) loadstring the custom message (I don't have any experience with loadstring)
I'm wondering:

• how to pass any arguments/variables into a loadstring function (if possible)
• or how to get the "environment" which contains the variables (I don't understand anything yet about environments)

This example seems to work for global variables:

foo = "bar"
local func = loadstring("return foo")
print(func()) [COLOR="DarkGreen"]-- prints "bar"[/COLOR]


Question A: But why does this example not work for upvalue variables? Does it maybe have something to do with the current "environment"?

local foo = "bar"
local func = loadstring("return foo")
print(func()) [COLOR="DarkGreen"]-- prints nil?![/COLOR]

Question B: And why is it the same for function argument variables?

local function test(arg1)
	loadstring("print(arg1)")()
end

test("Hello World!") [COLOR="DarkGreen"]-- prints nil?![/COLOR]

Eventually, I had something like this in mind; where a, b, and c are supposed to form the custom message
(.. thinking it over, I guess this example is also just fundamentally wrong )

a = "arg1"
b = "arg5"
c = "arg6"

local function test(arg1, arg2, arg3, arg4, arg5, arg6)
	loadstring("print(a, b, c)")()
end

test("Hi", "There", "Mister", "Smith", "Good", "Afternoon")
[COLOR="DarkRed"]-- prints "arg1 arg5 arg6" instead of my intended "Hi Good Afternoon"[/COLOR]



• Approach 2) gsub the custom message with the strings passed from my CLEU event handler

  local customMsg = "[SOURCE][SPELL] taunted [DEST]"
  
  local function gsubfunc(msg, sourceName, destName, spellName)
  	msg = msg:gsub("%[SOURCE%]", sourceName)
  	msg = msg:gsub("%[DEST%]", destName)
  	msg = msg:gsub("%[SPELL%]", spellName)
  	return msg
  end
  
  print(gsubfunc(customMsg, "[Foo]", "[Bar]", "[Growl]"))
  [COLOR="DarkRed"]-- "[Foo][Growl] taunted [Bar]"[/COLOR]

Quote from Starinnia

I went the gsub route in RealIDToons.

The user can set a string in the config that contains certain escape codes, then you can fill a table with all the information with the replacements as the key, pass the table to gsub and Lua does all the replacements for you.

The pattern I use only allows 1 upper or lower case letter for the replacement (ie. %t, %T, %l... etc) but you could change that around.
[...]
This is more simple than creating an environment for your loadstring calls like in LuaTexts. Not sure which approach is the most efficient for a combat log addon... maybe somebody has more insight than me.

Quote from Farmbuyer

You may want to try some of the approaches described here:

http://lua-users.org/wiki/StringInterpolation

Quote from sapu94

Basically it doesn't matter where you call loadstring from, it will always use the global environment (assuming you don't mess with setting the environment or anything) rather than taking into account the environment from which the function is called. That's why your "Question A" and "Question B" code both returned nil.

PS: A simple implementation of assert if your curious what it does:

[...]

It's useful for loadstring because if the string you are trying to load into a function causes a complier error, loadstring will return nil as the first value and an error message as the second. Doing loadstring inside an assert will cause any errors to go to the default error handler (ie show up in wow) rather than it just being a silent failure.