Addons and C++

[cincture]

Could someone please help me? I am trying to understand how the WoW interface and addons communicate with the MaNGOS emulator.

Blizzard_AuctionUI.xml shows this script on the Auction House BID button:

<OnClick>
	PlaceAuctionBid("list", GetSelectedAuctionItem("list"), MoneyInputFrame_GetCopper(BrowseBidPrice));
	self:Disable();			
</OnClick>

Blizzard_AuctionUI.lua also calls the function, but does not define it (most likely because addons should not be able to add/remove money)

PlaceAuctionBid(AuctionFrame.type, GetSelectedAuctionItem(AuctionFrame.type), AuctionFrame.buyoutPrice);

And the MaNGOS file AuctionHouse.cpp has this function defined, which appears to execute the PlaceAuctionBid call:

void WorldSession::HandleAuctionPlaceBid( WorldPacket & recv_data ) { ... }

My question is, how does clicking the BID button on the auction house call the HandleAuctionPlaceBid function in MaNGOS? Where is the code that makes the call to PlaceAuctionBid execute the HandleAuctionPlaceBid function? And, in general, how do Lua and C++ communicate with each other?

Thanks!

[AngelSandy]

It's very simple.

Lua is an "easier" version of C++. In general anyway.
With Lua, you recall functions already defined in the Core and use them. The huge plus about Lua is that it's a light weight language, and doesn't need to be recompiled, but only reloaded.

There is a limitation to Lua, as it can't do all the things that C++ can do. Look at it like this:
C++ is God
Lua is Jesus

God can do anything.
Jesus can only do things to a certain extent.

I hope this helped a bit Lol :b

[Link_S]

It's very simple.

Lua is an "easier" version of C++. In general anyway.

No Lua isn't an "easier" version of C++. You can see the difference clearly when you look at code that does the same thing.


And Mangos didn't have Lua support last time I checked :P

Sorry cincture but I don't know how to make "addons" for Mangos servers.

[cincture]

Ok, now my noobness is going to really show. What exactly does it mean when an emulator doesn't have "lua support"?

[Jotox]

Okay this is really stupid.

The LUA in that code that you posted does not cause the mangos code to execute.

What happens is that when you press the button, the LUA in that code you posted calls a C++ function written in the WoW client, and that C++ function sends a packet to the mangos server.

The mangos server receives the packet, and sends the packet to its correct code handler, meaning that C++ mangos function that you posted.


Does that explain it?

[AngelSandy]

^
What he says xD

[The-Eradicator]

Aside from Jotox, you guys clearly didn't read the thread.

He's asking about clientside Lua, not serverside.


For OP, Jotox is 100% correct. The only thing he omitted is that somewhere in the core (I don't know where exactly, I use TrinityCore), it routes specific packets, such as the one you're asking about, to their proper functions.


Note for you: Since it's pretty clear what you're probably leaning towards, yes, you can make addons that get data from the server. You can't add your own functions and have serverside handlers for them, but what you can do is use addon messages. You can manipulate data or send entirely different stuff to players from the addon message handlers.

[cincture]

Excellent. Thank you all. It's starting to make much more sense.

I found where the packets are rerouted in opcodes.cpp. It sounds like the specific code I was asking about is hard coded into the client, so I wouldn't be able to view it. I just wanted to see it, not alter it, so I'll just have to accept that that part of the code is "invisible."

Thanks for the help! I really appreciate it!