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UnLua相关

发表于 更新于
作者 JunQiang
3 分钟阅读

UnLua相关

C++ 怎么导出类给Lua

不导出能调用吗

  • 反射系统动态导出

怎么编写自己的C++业务封装给Lua

  • 工具函数和常规写c库的的方式一样
  • 库函数注册流程 EXPORT_UNTYPED_CLASS 、 IMPLEMENT_EXPORTED_CLASS
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namespace {
	template<typename ViewType>
	int32 UI_GetWidgetFromName(lua_State* L)
	{
		int32 NumParams = lua_gettop(L);
		if (NumParams != 2)
		{
			UNLUA_LOGERROR(L, LogUnLua, Log, TEXT("%s: Invalid parameters!"), ANSI_TO_TCHAR(__FUNCTION__));
			return 0;
		}

		ViewType* View = Cast<ViewType>(UnLua::GetUObject(L, 1));
		const char* WidgetName = lua_tostring(L, 2);

		UWidget* Widget = View->GetWidgetFromName(WidgetName);

		UnLua::PushUObject(L, Widget);
		return 1;
	}
}
class MiscUtils {};
static const luaL_Reg MiscUtilsLib[] =
{
	{ "GetWidgetFromName",      UI_GetWidgetFromName<UUserWidget> },
	{ nullptr, nullptr }
};

EXPORT_UNTYPED_CLASS(MiscUtils, false, MiscUtilsLib)
IMPLEMENT_EXPORTED_CLASS(MiscUtils)

初始化流程

Lua_State

  • 依托于 IModuleInterface 的生命周期初始化

  • 依托于 引擎的事件回调 执行 env 清理

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    class FUnLuaModule : public IModuleInterface
{
public:
    virtual void StartupModule() override
    {
    	FLuaContext::Create();
        GLuaCxt->RegisterDelegates();
    }

    virtual void ShutdownModule() override
    {
    }
};

Lua脚本静态绑定

  • 监听 UObject的引擎事件

    • FUObjectArray::FUObjectCreateListener

    • FUObjectArray::FUObjectDeleteListener

  • 执行 Lua脚本的绑定

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    bool FLuaEnv::TryBind(UObject* Object)
{
	// ...
    UFunction* Func = Class->FindFunctionByName(FName("GetModuleName"));
    // ...
    FString ModuleName;
    UObject* CDO = bIsCDO ? Object : Class->GetDefaultObject();
    CDO->ProcessEvent(Func, &ModuleName);
    // ...
    
    return GetManager()->Bind(Object, *ModuleName, GLuaDynamicBinding.InitializerTableRef);
}

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    bool UUnLuaManager::Bind(UObject *Object, const TCHAR *InModuleName, int32 InitializerTableRef)
{
    // ...
    UnLua::FLuaRetValues RetValues = UnLua::Call(L, "require", TCHAR_TO_UTF8(InModuleName));    // require Lua module
    // ...
    if (!RetValues.IsValid() || RetValues.Num() == 0)
    {
        Error = "invalid return value of require()";
        bSuccess = false;
    }
    else if (RetValues[0].GetType() != LUA_TTABLE)
    {
        Error = FString("table needed but got ");
        if(RetValues[0].GetType() == LUA_TSTRING)
            Error += UTF8_TO_TCHAR(RetValues[0].Value<const char*>());
        else
            Error += UTF8_TO_TCHAR(lua_typename(L, RetValues[0].GetType()));
        bSuccess = false;
    }
    else
    {
        bSuccess = BindInternal(Class, InModuleName, bMultipleLuaBind, Error);                             // bind!!!
    }
    
    if (bSuccess)
    {   
        FString RealModuleName = *ModuleNames.Find(Class);

        // create a Lua instance for this UObject
        Env->GetObjectRegistry()->Bind(Object, TCHAR_TO_UTF8(*RealModuleName));

        // try call user first user function handler
        int32 FunctionRef = PushFunction(L, Object, "Initialize");                  // push hard coded Lua function 'Initialize'
        if (FunctionRef != LUA_NOREF)
        {
            if (InitializerTableRef != LUA_NOREF)
            {
                lua_rawgeti(L, LUA_REGISTRYINDEX, InitializerTableRef);             // push a initializer table if necessary
            }
            else
            {
                lua_pushnil(L);
            }
            bool bResult = ::CallFunction(L, 2, 0);                                 // call 'Initialize'
            if (!bResult)
            {
                UE_LOG(LogUnLua, Warning, TEXT("Failed to call 'Initialize' function!"));
            }
            luaL_unref(L, LUA_REGISTRYINDEX, FunctionRef);
        }
    else
    {
        UE_LOG(LogUnLua, Warning, TEXT("Failed to attach %s module for object %s,%p!\n%s"), InModuleName, *Object->GetName(), Object, *Error);
    }

    return bSuccess;
}

Lua文件的加载是如何控制的

  • Unlua_2.2.2 - LuaEnv.cpp
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    FLuaEnv::FLuaEnv()
    {
    	// ...
    	
        AddSearcher(LoadFromCustomLoader, 2);
        AddSearcher(LoadFromFileSystem, 3);
        AddSearcher(LoadFromBuiltinLibs, 4);
        
        // ...
}

NewObject的Lua扩展

  • LoadObject
  • LoadClasss
  • NewObject

https://github.com/Tencent/UnLua/blob/master/Plugins/UnLua/Source/UnLua/Private/UELib.cpp

Lua, Unreal-Unlua
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