getmetatable - confuses me...

[kerrang]

I was looking through the OmniCC addon to find out how it hooks into the Cooldown functionality of Action Buttons.

I understand the theory - but the way it does it is either VERY clever or VERY obscure - I was hoping someone might explain it

The code is roughly

local methods = getmetatable(CreateFrame('Cooldown', nil, nil, 'CooldownFrameTemplate')).__index
hooksecurefunc(methods, 'SetCooldown', function(self, start, duration)
[function content here]
end)

What on EARTH is that getmetatable function returning - apart from 'a list of all the action buttons in the entire UI' - and how - what - where - who - when etc.

[zariel]

tables can have metatables.

getmetatable will return a table, usualy containg the keys, __index, __newindex, __call, __tostring, __metatable.

What its doing is creating a button, getting the metatable and then __index key which is also a table.

Frames work by using metatables as a kind of prototype to setup shared functions.

Metatables are discussed here in the pil manual http://www.lua.org/pil/13.html

[Akryn]

Originally Posted by kerrang local methods = getmetatable(CreateFrame('Cooldown', nil, nil, 'CooldownFrameTemplate')).__index hooksecurefunc(methods, 'SetCooldown', function(self, start, duration) [function content here] end)

(edit: maybe you understand this and just wanted to know what metatables are...in that case see above :P)

doing this out at greater lenght might be useful:

local f = CreateFrame('Cooldown', nil, nil, 'CooldownFrameTemplate')
local mTable = getmetatable(f)
local methods = mTable.__index

hooksecurefunc is then hooking the function SetCooldown within methods