Warlock resources bar problem

[Rainrider]

Here is my try at the warlock resources bar: https://gist.github.com/Rainrider/5246884

However, when testing this on a toon that does not have the prereq spells, I get the following error:

oUF: Error: Style [Rain] attempted to register event [SPELLS_CHANGED] on unit [player] with a handler that doesn't exist.

I checked Phanx' code as a reference and it seems to me (s)he does the same thing: registers the handler for the event from within the handler, but does not have any errors.

Could someone explain the difference I fail to see please?

[Phanx]

That error means that you wrote the wrong function name in your RegisterEvent call, or have a scoping issue. To avoid scoping issues, I usually define all my function names first, and then the functions:

local Visibility, Update, Path, ForceUpdate, Enable, Disable

function Visibility(self, event)
    -- stuff
end

function Update(self, event)
    -- stuff
end

-- etc

[Rainrider]

Thanks for the reply Phanx. Upvaluing Visibility solved it. The other way was using

local function Visibility(self)

instead of

local Visibility = function(self)

I thought the first one is just syntactic sugar for the second, but apparently it's not just that. Could someone please explain that?

[Phanx]

It's slightly different. There's a post somewhere on WowAce where someone explained it in a bit more detail, but basically "local function x() end" works like "make a function named x, and then make it local" while "local x = function() end" works like "make a function, and then assign it to the local variable x"... it's executed from right to left, so with the latter, the function is defined first, and then the variable, so if you try to call "x" from inside the function, the "local x" part hasn't been defined yet, and you're looking for a global "x" which probably doesn't exist, and won't be what you want even if it does.

local function print(x)
    UIErrorsFrame:AddMessage(x)
    if x == "Hello" then
        print("Hello to you too")
    end
end
print("Hello")

^ The inner "print" refers to the "local function print", so both messages go to the UIErrorsFrame.

local print = function(x)
    UIErrorsFrame:AddMessage(x)
    if x == "Hello" then
        print("Hello to you too")
    end
end
print("Hello")

^ The inner "print" refers to the global "print", so "Hello" goes to the UIErrorsFrame, but "Hello to you too" goes to the DEFAULT_CHAT_FRAME.

[haste]

local function func() end
-- is sugar for:
local func;
func = function() end
 
-- Also note that:
local func = function()
   print(func) -- prints nil
end
local function func()
   print(func) -- funcction: 0xHEX
end