Extending/Hooking each widgets' Blizzard default API

[seyan777]

Wassup!

Again, the title says pretty much all.

What I am trying to achieve here is to create a new function or extend an existing function of widget objects.

However, each widget objects won't have all the same functions.

For example, Frame object will have :StartMoving() & :StopMovingOrSizing(), while FontString object won't.

I am aware of that by accessing metatable of each objects, you can modify or create a function.

The only problem that I am currently facing is getting a list of all widget objects without hard coding them.

Any ideas, please?

Cheers!

[Lombra]

I don't understand what you're looking for exactly. A list of object types, such as Frame, Button, Texture, etc? What are you doing that requires that which you are looking for?

[MunkDev]

It's very unclear what exactly you want to achieve, so it might be better if you provide a use case since there might be better ways to do it than hooking metatable functions.

[SDPhantom]

You could do something like this.

local WidgetMeta={};
for frame in function(_,last) return EnumerateFrames(last); end do
    local objtype=frame:GetObjectType();
    if not WidgetMeta[objtype] then WidgetMeta=getmetatable(frame).__index; end
 
    for _,region in ipairs({frame:GetRegions()}) do
        local objtype=region:GetObjectType();
        if not WidgetMeta[objtype] then WidgetMeta=getmetatable(region).__index; end
    end
end

This should grab every widget type, except maybe the animation system, and put their metatable functions in WidgetMeta. Note, frame:GetChildren() scanning is omitted because EnumerateFrames() covers them anyway.

[seyan777]

Okay, I'll try to be more specific!

Let's say I want to modify the :StartMoving() function for all widget objects which owns that function.
(Objects may include "Frame", "Button", "StatusBar", etc.)

Like MunkDev stated, I could access index of each object types' metatable to modify that function.

local oldFunctions = oldFunctions or {};
 
local function _StartMoving(self)
    oldFunctions[self:GetObjectType()]["OldStartMoving"](self);
 
    -- do some extra stuff here
end
 
local index = getmetatable(object).__index;
 
oldFunctions[object:GetObjectType()] = oldFunctions[object:GetObjectType()] or {};
 
if object.StartMoving then
    oldFunctions[object:GetObjectType()]["OldStartMoving"] = object.StartMoving;
 
    index.StartMoving = _StartMoving;
end

So, now I need a list of object types to apply this approach, but that's exactly where I am having difficulties with.

TL;DR: Need a method to get all object types.

Cheers!

[seyan777]

Originally Posted by SDPhantom You could do something like this. local WidgetMeta={}; for frame in function(_,last) return EnumerateFrames(last); end do     local objtype=frame:GetObjectType();     if not WidgetMeta[objtype] then WidgetMeta=getmetatable(frame).__index; end       for _,region in ipairs({frame:GetRegions()}) do         local objtype=region:GetObjectType();         if not WidgetMeta[objtype] then WidgetMeta=getmetatable(region).__index; end     end end This should grab every widget type, except maybe the animation system, and put their metatable functions in WidgetMeta. Note, frame:GetChildren() scanning is omitted because EnumerateFrames() covers them anyway.

Awesome!

Since, what I needed was a widget type rather than functions I have modified it to following and works like a charm

local WidgetMeta = {};
for frame in function(_, last) return EnumerateFrames(last); end do
    local objtype = frame:GetObjectType();
 
    if not WidgetMeta[objtype] then
        WidgetMeta[objtype] = true;
    end
 
    for _, region in ipairs({frame:GetRegions()}) do
        local objtype = region:GetObjectType();
 
        if not WidgetMeta[objtype] then
            WidgetMeta[objtype] = true;
        end
    end
end

Thank you, SDPhantom!

But, I still don't get how that annoymous function in first for loop works.

Where does it get those parameters (_ and last)?

[MunkDev]

Originally Posted by seyan777 But, I still don't get how that annoymous function in first for loop works. Where does it get those parameters (_ and last)?

It's a custom iterator. EnumerateFrames is a utility function that works similarly to next, in that it returns the first frame in a list, and when you provide the returned frame back to the same function, it'll return the second frame in the list. It'll keep doing this until it runs out of frames.

This could otherwise be implemented as a while loop:

local numFrames = 0
local frame = EnumerateFrames()
while frame do
    numFrames = numFrames + 1
    frame = EnumerateFrames(frame)
end
 
print(numFrames)

[SDPhantom]

Originally Posted by seyan777 Let's say I want to modify the :StartMoving() function for all widget objects which owns that function. (Objects may include "Frame", "Button", "StatusBar", etc.) Like MunkDev stated, I could access index of each object types' metatable to modify that function. local oldFunctions = oldFunctions or {};   local function _StartMoving(self)     oldFunctions[self:GetObjectType()]["OldStartMoving"](self);       -- do some extra stuff here end   local index = getmetatable(object).__index;   oldFunctions[object:GetObjectType()] = oldFunctions[object:GetObjectType()] or {};   if object.StartMoving then     oldFunctions[object:GetObjectType()]["OldStartMoving"] = object.StartMoving;       index.StartMoving = _StartMoving; end

A more efficient way to go at this would be to combine the code I already posted with the following:

local Hooks={};
 
function Hooks:StartMoving()
--  Do something with frame:StartMoving()
end
 
function Hooks:StopMovingOrSizing()
--  Do something with frame:StopMovingOrSizing()
end
 
for key,func in pairs(Hooks) do
    for _,meta in pairs(WidgetMeta) do
        if meta[key] then hooksecurefunc(meta,key,func); end
    end
end

This goes through all of the metatables and hooks the functions matching the name stored in Hooks. No need to create or search for the widget type you need to hook or grab their metatables since that was already done. Using hooksecurefunc() also deals with setting up the hooks and does so without causing taint that could possibly cripple the rest of the UI.

Originally Posted by seyan777 But, I still don't get how that annoymous function in first for loop works. Where does it get those parameters (_ and last)?

Those two parameters for the first iteration are given from what's supplied after the function in the for declaration. Since these are both omitted, they'll be nil for the first run. For each iteration after, the first parameter will be the same while the second will be what this function returned the last time. If the function returns multiple values, this will always be the first one. The loop ends when the function returns nil.

[seyan777]

Cool!

Many thanks to both MunkDev and SDPhantom

You guys made my day !!

[seyan777]

Originally Posted by SDPhantom A more efficient way to go at this would be to combine the code I already posted with the following: local Hooks={};   function Hooks:StartMoving() --  Do something with frame:StartMoving() end   function Hooks:StopMovingOrSizing() --  Do something with frame:StopMovingOrSizing() end   for key,func in pairs(Hooks) do     for _,meta in pairs(WidgetMeta) do         if meta[key] then hooksecurefunc(meta,key,func); end     end end This goes through all of the metatables and hooks the functions matching the name stored in Hooks. No need to create or search for the widget type you need to hook or grab their metatables since that was already done. Using hooksecurefunc() also deals with setting up the hooks and does so without causing taint that could possibly cripple the rest of the UI.

Just tested it now and am facing an issue with the nested for loop.

Hooks = {};
WidgetMeta = {};
 
function Hooks:StartMoving(obj)
    print("Hooks:StartMoving");
end
 
function Hooks:StopMovingOrSizing(obj)
    print("Hooks:StopMovingOrSizing");
end
 
for frame in function(_, last) return EnumerateFrames(last); end do
    local objtype = frame:GetObjectType();
 
    if not WidgetMeta[objtype] then
        WidgetMeta = getmetatable(frame).__index;
    end
 
    for _, region in ipairs({frame:GetRegions()}) do
        local objtype = region:GetObjectType();
 
        if not WidgetMeta[objtype] then
            WidgetMeta = getmetatable(region).__index;
        end
    end
end
 
for key, func in pairs(Hooks) do
    for _, meta in pairs(WidgetMeta) do
        if meta[key] then
            hooksecurefunc(meta, key, func);
        end
    end
end

Since meta is in fact a function itself, if statement on inner for loop errors out as it is trying to index a function.

Thus, I have switched that part to following:

for key, func in pairs(Hooks) do
    if WidgetMeta[key] then
        hooksecurefunc(WidgetMeta, key, func);
    end
end

No errors popped up!

However, whenever :StartMoving() & :StopMovingOrSizing() functions were called, it did not print out those strings.

So, I checked WidgetMeta table and it did not have :StartMoving() & :StopMovingOrSizing() functions

Any ideas, please?!

Cheers!

[MunkDev]

You forgot the indices when copying from the metatable on the widget to your table. You keep overwriting the table with whatever the last frame/region was in your loop. Note that meta is a function in your example because you made this error. You're actually looping over a metatable, not a table of metatables. In the example below, meta will always be a table.

Hooks = {};
WidgetMeta = {};
 
function Hooks:StartMoving() -- when using colon, the object itself will be accessible as self
    print("Hooks:StartMoving", self:GetName());
end
 
function Hooks:StopMovingOrSizing()
    print("Hooks:StopMovingOrSizing", self:GetName());
end
 
for frame in function(_, last) return EnumerateFrames(last); end do
    local objtype = frame:GetObjectType();
 
    if not WidgetMeta[objtype] then
        WidgetMeta[objtype] = getmetatable(frame).__index;  -- fixed
    end
 
    for _, region in ipairs({frame:GetRegions()}) do
        local objtype = region:GetObjectType();
 
        if not WidgetMeta[objtype] then
            WidgetMeta[objtype] = getmetatable(region).__index; -- fixed
        end
    end
end
 
for key, func in pairs(Hooks) do
    for _, meta in pairs(WidgetMeta) do
        if meta[key] then
            hooksecurefunc(meta, key, func);
        end
    end
end

[seyan777]

Originally Posted by MunkDev You forgot the indices when copying from the metatable on the widget to your table. You keep overwriting the table with whatever the last frame/region was in your loop. Note that meta is a function in your example because you made this error. You're actually looping over a metatable, not a table of metatables. In the example below, meta will always be a table.

That depresses me so much

How stupid I could be...

Thanks for correcting it, MunkDev!!