Fio:LuaBinder
From Fio
(→Lua Binder) |
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===Quick Tour=== | ===Quick Tour=== | ||
| + | Thru the lua API, we can create a metatable and register our c++ class' member functions there. Then we associate that metatable with the according c++ object(lurk in lua as a userdata). Later when a function call happens on that object, it'll finally invoke the registered member function. The [http://www.lua.org/pil/28.3.html Object-Oriented Access] chapter of [http://www.lua.org/pil Programming in Lua] describes this process in detail. | ||
===The Lua Application Program Interface=== | ===The Lua Application Program Interface=== | ||
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*normal | *normal | ||
*lightweight | *lightweight | ||
| + | *why userdata is not enough? | ||
===Method Invoking=== | ===Method Invoking=== | ||
Revision as of 15:01, 18 September 2006
"Like a bridge over troubled water..." - Simon and Garfunkel
still in ctoring
Contents |
Lua Binder
Fio use Lua as scripting language to implement the game logic which include(in a broad sense):
- UI design and switching
- event handler
- combat scheduler
- npc behavior
All the logics/policies are build on the mechanisms carried out by c++ classes which will do the real work of rendering, timing, event dispatching etc. This separation is to make the game fully data driven - thru scripting the logic itself is taken as data which can be easily modified without the re-compile-link of the mechanism part(or the engine).
Lua has provided a bunch of APIs for "the host program to communicate with Lua". To call function from lua into c++, we have to:
- extract the arguments from lua stack;
- check the argument/return value type;
- call c++ function;
- push the return value onto lua stack;
- take care the return value's lifetime.
thru Lua APIs.
As the number of classes needs to be embedded into lua increases, these routine work will be a burden to write and maintain for each function call. There're quite a few binders out there to make the embedding easier. In Fio we implement a home brew binder - LuaUtil as a bridge between the c++ and lua world.(Not-Invented-Here Syndrome? no, it's just for better understanding of the scripting and faster compiling speed)
Quick Tour
Thru the lua API, we can create a metatable and register our c++ class' member functions there. Then we associate that metatable with the according c++ object(lurk in lua as a userdata). Later when a function call happens on that object, it'll finally invoke the registered member function. The Object-Oriented Access chapter of Programming in Lua describes this process in detail.
The Lua Application Program Interface
Construct An Object
- normal
- lightweight
- why userdata is not enough?
Method Invoking
- method wrap
from lua into c++
- traits
- Overload
from c++ into lua
callback?
Type Checking
LSP
Destruct & Object Lifetime in the 2 Worlds
Misc
- const
- panic
- utility functions
