Why doesn't this function work?

[MysteryPancake]

Yes, me again. Don't worry though, this is probably a stupid problem that will be easy to solve. I have a function that should help with creating a lot of buttons on a vgui, but I have a problem, when I try to print the vgui button that should have been created by this function, it keeps returning 'nil'. I simplified the code quite a lot, and I'm pretty horrible at localizing, so the problem probably lies around something like that.

local function ButtonCreate(buttonname, buttonsize, buttontext, extraargs)
	local buttonname = self.list:Add( "DButton" )
	buttonname:SetSize( buttonsize, 70 )
	buttonname:SetText( buttontext )
	extraargs()
	return buttonname
end

ButtonCreate(buttontest, 200, "Make the victim say something!", function()
print(buttontest)
end)

I'm sure it's something obvious I missed.

[editline]30th March 2015[/editline]

By the way, I left out self.list from the example, as it shouldn't matter.

[James]

Firstly, you are asking for an argument that you overwrite in the first line. Secondly, you pass a nil argument (Buttontest is undefined) to the function. Thirdly, same thing for print. Fourthly, you don't have access to a the self variable in this instance. Only when you are defining a function like this do you have access to it:

[lua]function Meta:Func() end [/lua]

In Lua, you can't pass references like in C++. What you want to achieve is done like this:

[lua]
local function ButtonCreate(buttonname, buttonsize, buttontext, extraargs)
_G[buttonname] = self.list:Add( "DButton" )
_G[buttonname]:SetSize( buttonsize, 70 )
_G[buttonname]:SetText( buttontext )
extraargs()
return _G[buttonname] -- No idea why you are returning it but sure.
end

ButtonCreate("buttontest", 200, "Make the victim say something!", function()
print(buttontest)
end)
[/lua]

[MysteryPancake]

I want the button to be local though (to the code calling the function), and _G means global, right? Or, just global to the code calling it (if that makes sense)?

[James]

[QUOTE=MPan1;47422230]I want the button to be local though (to the code calling the function), and _G means global, right? Or, just global to the code calling it (if that makes sense)?[/QUOTE]

That makes sense, the way you formulating your code made be think you wanted them global. For local instances, you would do it like this:

[Lua]
local function ButtonCreate( buttonsize, buttontext, extraargs)
local buttonname = self.list:Add( "DButton" )
buttonname:SetSize( buttonsize, 70 )
buttonname:SetText( buttontext )
extraargs()
return buttonname
end

local buttontest = ButtonCreate(200, "Make the victim say something!", function()
print(buttontest)
end)

[/lua]

[Lixquid]

[QUOTE=James xX;47422235]That makes sense, the way you formulating your code made be think you wanted them global. For local instances, you would do it like this:

[Lua]
local function ButtonCreate( buttonsize, buttontext, extraargs)
local buttonname = self.list:Add( "DButton" )
buttonname:SetSize( buttonsize, 70 )
buttonname:SetText( buttontext )
extraargs()
return buttonname
end

local buttontest = ButtonCreate(200, "Make the victim say something!", function()
print(buttontest)
end)

[/lua][/QUOTE]

Note that this'll still print nil because buttontest hasn't been assigned when extraargs() is run.

You should probably do this:
[lua]
local function ButtonCreate( buttonsize, buttontext, extraargs)
local buttonname = self.list:Add( "DButton" )
buttonname:SetSize( buttonsize, 70 )
buttonname:SetText( buttontext )
extraargs()
return buttonname
end

local buttontest = ButtonCreate(200, "Make the victim say something!")
print(buttontest)
[/lua]

If, however, you desperately want to manipulate it in a callback, you can pass it as an argument.

[lua]
local function ButtonCreate( buttonsize, buttontext, extraargs)
local buttonname = self.list:Add( "DButton" )
buttonname:SetSize( buttonsize, 70 )
buttonname:SetText( buttontext )
extraargs( buttonname )
return buttonname
end

local buttontest = ButtonCreate(200, "Make the victim say something!", function(buttontest)
print(buttontest)
end)
[/lua]

[MysteryPancake]

@Lixquid Yep, I desperately wanted to manipulate it! Thanks a LOT!