Function to setup dragging & save the vars

[stako]

Hello,

I'm sure everybody is familiar with making a frame movable and saving its position by doing something like this:

frame:SetScript("OnMouseDown", function()
    if not frame.isMoving then
        frame:StartMoving()
        frame.isMoving = true
    end
end)
 
frame:SetScript("OnMouseUp", function()
    if frame.isMoving then
        frame:StopMovingOrSizing()
        frame.isMoving = false
        
        MyAddon.db.profile.position = {frame:GetPoint()}
    end
end)

Now I'm doing this for numerous frames, so I'm trying to make a function out of it:

function MyAddon:SetupDrag(frame, dbsetting)
    frame:SetScript("OnMouseDown", function()
        if not frame.isMoving then
            frame:StartMoving()
            frame.isMoving = true
        end
    end)
 
    frame:SetScript("OnMouseUp", function()
        if frame.isMoving then
            frame:StopMovingOrSizing()
            frame.isMoving = false
            
            -- Parameters get passed as values, so this won't work
            -- dbsetting = {frame:GetPoint()}
            
            -- This works
            dbsetting[1], dbsetting[2], dbsetting[3], dbsetting[4], dbsetting[5] = frame:GetPoint() 
        end
    end)
end

And example function call:
MyAddon:SetupDrag(ExampleFame, MyAddon.db.profile.position)

This works a little. Once I reset or change Ace profiles, it stops functioning. I think after the profile changes, MyAddon.db.profile.position will reference properly, but dbsetting will not?

Can't figure out a fix for that. Any ideas?

[MunkDev]

It's fine to alter a table in one place and maintain a reference to it in another place, as long as you don't replace the table as a whole. Your variables are just pointers to the same object in memory. The code you posted isn't enough to figure out the cause.

[SDPhantom]

Long story short, the variables don't actually store the table itself. They store a pointer that tells Lua where the table data is. This means when the Ace profile changes, dbsetting remains pointing to the old table. You need to call MyAddon:SetupDrag() again to update, but there is already an inherent problem in doing so. You're wasting resources dynamically creating new functions every time you call it. To prevent this, you should create static versions of them as upvalues so they don't get recreated constantly. To handle saving their positions, each frame called in the code below will store a reference to its own profile table. Again, you still need to call MyAddon:SetupDrag() each time the profile changes to update these references.

local function Frame_OnMouseDown(self)
    if not self.isMoving then   
        self:StartMoving()
        self.isMoving = true
    end
end
 
local function Frame_OnMouseUp(self)
    if self.isMoving then
        self:StopMovingOrSizing()
        self.isMoving = false
 
        self.settings[1], self.settings[2], self.settings[3], self.settings[4], self.settings[5] = self:GetPoint(1)
    end
end
 
function MyAddon:SetupDrag(frame, settings)
    frame.settings=settings
    frame:SetScript("OnMouseDown", Frame_OnMouseDown)
    frame:SetScript("OnMouseUp", Frame_OnMouseUp)
end

PS: frame:GetPoint() needs an index saying which point you want. I'm surprised this hasn't thrown an error.

[stako]

Thank you very much!

Also hadn't even thought about GetPoint() needing an argument. I think I can use GetCenter() instead.

[SDPhantom]

Be aware if you use frame:GetCenter(), the numbers you get may be raw coordinates not taking into account UI scaling or anchor offsets. In this case, it's based off the coordinates at the bottom left corner of the screen. To reapply these numbers, the point you set would have to be the center of the frame. When you apply a profile change for example, be sure to call frame:ClearAllPoints() to make sure if the UI moved which point was set when dragged around, it wouldn't cause any further problems before setting the new position.

It might be better in the long run instead of frame:GetPoint() since saved vars can't store frame references, which would be its second return.