Determining a frame from a normal table?

[Brusalk]

Hey There!

So in my addon I need to find a way to differentiate between a table value and a frame value (or texture, fontString, etc).

I've been trying to figure it out, and I can't seem to figure out a way to differentiate it without throwing an error that the method doesn't exist. Type(tableorframename) returns table regardless.


To be clear: I'm trying to do something like

if IsFrame(temp) then -- do stuff since it's a frame
elseif type(temp) == "table" then -- do other stuff since it's a table and not a frame
else -- idk
end

And no, I'm not trying to make a frame if it doesn't exist, I'm trying to differentiate between a table and a frame/widget.


Thanks!
-Brusalk

[Barjack]

There may be a more sophisticated way to do this, but you don't need to call a function to find out if it exists or not, so you can use that to kind of check whether something is (probably) a widget. For example:

if (obj.GetObjectType) then
  -- it's a widget of some sort
  if (obj:GetObjectType() == "Frame") then
    -- do whatever. could also be "Button", "StatusBar", etc.
  end
else
  -- it's a table
end

Of course if someone actually defines a GetObjectType on their table which isn't really a frame, this might backfire. I don't know if that's actually relevant for your purposes though.

[Phanx]

Originally Posted by Brusalk So in my addon I need to find a way to differentiate between a table value and a frame value (or texture, fontString, etc).

For most purposes:

if type(object) == "table" then
     if object.GetObjectType then
          -- it's a frame, texture, font string, or other UI widget
     else
          -- it's a table
     end
end

Slightly slower but slightly more foolproof if you're worried about tables "pretending" to be widgets by defining GetObjectType or methods on themselves:

if type(object) == "table" then
    if type(object[0]) == "userdata" then
        -- it's a widget
    else
        -- it's a table
    end
end

[Brusalk]

Awesome, thanks!

I tried doing a /run print(type(tableVar[0])) and it was returning table when I tried to do that last night. (I defined tableVar as a global frame by /run tableVar = CreateFrame("frame")


On another note, is there a way to make your own UI widget that new frames can inherit off of? I'm working in my addon with a frame which contains a bunch of methods and variables which I'm interested in duplicating (exactly the same as creating a frame which inherits something like a PaperDollFrame or something like that)

[Dridzt]

Originally Posted by Brusalk Awesome, thanks! I tried doing a /run print(type(tableVar[0])) and it was returning table when I tried to do that last night. (I defined tableVar as a global frame by /run tableVar = CreateFrame("frame") On another note, is there a way to make your own UI widget that new frames can inherit off of? I'm working in my addon with a frame which contains a bunch of methods and variables which I'm interested in duplicating (exactly the same as creating a frame which inherits something like a PaperDollFrame or something like that)

There's 2 ways (that I know) to do this.
a. Use xml for your template frame and set the virtual attribute to true Wowpedia: Using templates.
b. Use a frame constructor function that returns a frame if you want to achieve a similar effect in pure lua.

[Phanx]

local function NewItemButton()
	local button = CreateFrame("Button", nil, UIParent)
	button.text = button:CreateFontString(nil, "OVERLAY")
	button.icon = button:CreateTexture(nil, "OVERLAY")
	-- Set up scripts, regions, and other features
	-- that are shared by all buttons here.
end

local button1 = NewItemButton()
button1:SetPoint("CENTER", 0, 200)
-- Set points, icon textures, fontstring text, and other features
-- that are specific to this individual button here.

local button2 = NewItemButton()
button2:SetPoint("RIGHT", -100, 0)

Or, you can use a metatable:

local buttons = setmetatable({}, { __index = function(t, i)
	local button = CreateFrame("Button", nil, UIParent)
	button.text = button:CreateFontString(nil, "OVERLAY")
	button.icon = button:CreateTexture(nil, "OVERLAY")

	-- Set up scripts, regions, and other features
	-- that are shared by all buttons here.

	if i > 1 then
		-- Not the first button; attach to previous button
		button:SetPoint("TOP", buttons[i-1], "BOTTOM")
	else
		-- First button; no previous button to attach to
		button:SetPoint("TOP", UIParent, "CENTER", 0, 200)
	end

	t[i] = button
	return button
end })

for i = 1, 10 do
	-- This will create 10 buttons, even though you never explicitly call any functions to create them.
	local button = buttons[i]
	button.text:SetText("Button #"..i)
	button.icon:SetTexture("Interface\\Icons\\INV_Misc_QuestionMark")
end

Depending on what kind of objects you want to create, and how you're using them, one method will make more sense than the other. Both make more sense than XML though.

[Brusalk]

Is there a specific speed increase one way over the other and how does WoW/Lua handle the creation of frames using a metatable? Like, they do exactly the same thing, but does one require less memory or execution time or is one faster in completing execution?

When you're defining the metatable, there's __index = function(t, i). Is t a reference to the table that's created or is it a reference to the base object. (From brief reading of metatables in the Lua-man, I see that __index is a metamethod that is basically a catch-all) For example, say I wanted to make a series of new frames that all share some common properties.

I'd define a metatable (using setmetatable) giving it all the stuff you included in your example, letting me make a bunch of frames easily by indexing the metatable. Now, say I wanted to define methods on the created frames, such as returning a custom value contained in the frame. So I would add something like this?

local buttons = setmetatable({}, { __index = function(t, i)
	local button = CreateFrame("Button", nil, UIParent)
	button.text = button:CreateFontString(nil, "OVERLAY")
	button.icon = button:CreateTexture(nil, "OVERLAY")

	-- Set up scripts, regions, and other features
	-- that are shared by all buttons here.

        function button:GetIconTexture()
              return self.icon:GetTexture()
        end

	if i > 1 then
		-- Not the first button; attach to previous button
		button:SetPoint("TOP", buttons[i-1], "BOTTOM")
	else
		-- First button; no previous button to attach to
		button:SetPoint("TOP", UIParent, "CENTER", 0, 200)
	end
end })

for i = 1, 10 do
	-- This will create 10 buttons, even though you never explicitly call any functions to create them.
	local button = buttons[i]
	button.text:SetText("Button #"..i)
	button.icon:SetTexture("Interface\\Icons\\INV_Misc_QuestionMark")
        print(button:GetIconTexture()) -- prints "Interface\\Icons\\INV_MISC_QuestionMark"
end

So adding that would allow me to hide some commonly used implementation to clean up other sections of code, or am I wrong and misunderstanding something?

[SDPhantom]

Originally Posted by Phanx local buttons = setmetatable({}, { __index = function(t, i) local button = CreateFrame("Button", nil, UIParent) button.text = button:CreateFontString(nil, "OVERLAY") button.icon = button:CreateTexture(nil, "OVERLAY") -- Set up scripts, regions, and other features -- that are shared by all buttons here. if i > 1 then -- Not the first button; attach to previous button button:SetPoint("TOP", buttons[i-1], "BOTTOM") else -- First button; no previous button to attach to button:SetPoint("TOP", UIParent, "CENTER", 0, 200) end end }) for i = 1, 10 do -- This will create 10 buttons, even though you never explicitly call any functions to create them. local button = buttons[i] button.text:SetText("Button #"..i) button.icon:SetTexture("Interface\\Icons\\INV_Misc_QuestionMark") end

You need the __index metamethod to return a value or buttons[i] will still retrieve nil. Also to prevent the table from recreating extra buttons constantly, you should actually set the value in the table.