重新回头看Luabinding

重新回头看Luabinding， Windows平台

1. 需要的环境

• android-ndk-r10c，并配置环境变量NDK_ROOT。需要重启或者注销电脑生效
• python2.7.3 (32bit) from (http://www.python.org/ftp/python/2.7.3/python-2.7.3.msi).并配置环境变量，PATH下(e.g. C:\Python27)
• pyyaml http://pyyaml.org/download/pyyaml/PyYAML-3.11.win32-py2.7.exe 下载并安装
• pyCheetah from https://raw.github.com/dumganhar/my_old_cocos2d-x_backup/download/downloads/Cheetah.zip, 解压到Python安装目录 "C:\Python27\Lib\site-packages"

2. 自定义C++类'MyClass',我放在了runtime-src\Classes目录下面。

3. 修改ini文件

一般直接在 **\frameworks\cocos2d-x\tools\tolua目录下操作。复制一份cocos2dx_ui.ini，重命名my_class.ini， 然后进行修改，下面是我修改后的：

[my_class]
# the prefix to be added to the generated functions. You might or might not use this in your own
# templates
prefix = my_class

# create a target namespace (in javascript, this would create some code like the equiv. to `ns = ns || {}`)
# all classes will be embedded in that namespace
target_namespace = zwf

# the native namespace in which this module locates, this parameter is used for avoid conflict of the same class name in different modules, as "cocos2d::Label" <-> "cocos2d::ui::Label".
cpp_namespace = 

android_headers = -I%(androidndkdir)s/platforms/android-14/arch-arm/usr/include -I%(androidndkdir)s/sources/cxx-stl/gnu-libstdc++/4.7/libs/armeabi-v7a/include -I%(androidndkdir)s/sources/cxx-stl/gnu-libstdc++/4.7/include -I%(androidndkdir)s/sources/cxx-stl/gnu-libstdc++/4.8/libs/armeabi-v7a/include -I%(androidndkdir)s/sources/cxx-stl/gnu-libstdc++/4.8/include
android_flags = -D_SIZE_T_DEFINED_ 

clang_headers = -I%(clangllvmdir)s/lib/clang/%(clang_version)s/include 
clang_flags = -nostdinc -x c++ -std=c++11 -U __SSE__

cocos_headers = -I%(cocosdir)s/cocos -I%(cocosdir)s/cocos/editor-support -I%(cocosdir)s/cocos/platform/android

cocos_flags = -DANDROID

cxxgenerator_headers = 

# extra arguments for clang
extra_arguments = %(android_headers)s %(clang_headers)s %(cxxgenerator_headers)s %(cocos_headers)s %(android_flags)s %(clang_flags)s %(cocos_flags)s %(extra_flags)s 

# what headers to parse
headers = %(cocosdir)s/../runtime-src/Classes/MyClass.h

# what classes to produce code for. You can use regular expressions here. When testing the regular
# expression, it will be enclosed in "^$", like this: "^Menu*$".
classes = MyClass

# what should we skip? in the format ClassName::[function function]
# ClassName is a regular expression, but will be used like this: "^ClassName$" functions are also
# regular expressions, they will not be surrounded by "^$". If you want to skip a whole class, just
# add a single "*" as functions. See bellow for several examples. A special class name is "*", which
# will apply to all class names. This is a convenience wildcard to be able to skip similar named
# functions from all classes.

skip = 

rename_functions = 

rename_classes =

# for all class names, should we remove something when registering in the target VM?
remove_prefix = 

# classes for which there will be no "parent" lookup
classes_have_no_parents = Helper

# base classes which will be skipped when their sub-classes found them.
base_classes_to_skip =

# classes that create no constructor
# Set is special and we will use a hand-written constructor
abstract_classes = Helper AbstractCheckButton

# Determining whether to use script object(js object) to control the lifecycle of native(cpp) object or the other way around. Supported values are 'yes' or 'no'.
script_control_cpp = no

其中headers、classes、cpp_namespace是必须修改的。一般自定义的都不一样。
target_namespace标示的是到处的lua模块的命名空间，看个人喜好修改。
prefix这个是防止重命名的，一般都改成自定义的类应该就没问题了。
skip 不想导出的类级函数, 用于处理一些和lua不兼容的c++参数, 比如 std::function, std::pair 等, 这些参数没法通过栈空间传递给lua, 因此也就没办法导出给lua使用, 需要排除掉.

4. 执行脚本genbindings.py，生成绑定文件。
   执行脚本之前，先修改脚本的配置，只生成我们自定义类的绑定文件就行，

cmd_args = {
            'my_class.ini' : ('my_class', 'lua_myclass_auto'), \
            }

然后在**\frameworks\cocos2d-x\tools\tolua目录下运行脚本，等待生成就可以了。（尽量在这个目录下执行脚本，在其他目录有可能失败）

5.导入工程中使用。把新生成的lua_myclass_auto.hpp和lua_myclass_auto.cpp拷贝到runtime-src\Classes目录下，导入工程，然后注册一下就可以使用了，注册方法：

static int register_all_packages(lua_State*L)
{
    register_all_my_class(L);//这个是新加的注册方法
    return 0; //flag for packages manager
}

6.lua中调用

    local myClass = zwf.MyClass:new("1111") --注意构造函数绑定的时候暴露到lua中的接口
    myClass:printInfo()

到这里基本的binding流程就完成了。

需要注意的是自动binding并不支持std::function的回调，所以需要手动binding，贴一下我的C++代码和binding代码：
C++：

#pragma once
#include  //这个是std::function的头文件
#include
class MyClass
{
    //定义一个函数类型
    typedef std::function myCallBack;

public:
    MyClass(std::string name);
    ~MyClass();
    const std::string & getName();
    void setName(std::string name);
    void printInfo();

    //std::function作为参数传入
    void setCallBack(const myCallBack& callBack);
private:
    std::string _name;
    myCallBack _callBack;
};

binding代码：

int lua_my_class_MyClass_setCallBack(lua_State* tolua_S)
{
    int argc = 0;
    MyClass* cobj = nullptr;
    bool ok  = true;

#if COCOS2D_DEBUG >= 1
    tolua_Error tolua_err;
#endif


#if COCOS2D_DEBUG >= 1
    if (!tolua_isusertype(tolua_S,1,"MyClass",0,&tolua_err)) goto tolua_lerror;
#endif
    //获取对象
    cobj = (MyClass*)tolua_tousertype(tolua_S,1,0);

#if COCOS2D_DEBUG >= 1
    if (!cobj) 
    {
        tolua_error(tolua_S,"invalid 'cobj' in function 'lua_my_class_MyClass_setCallBack'", nullptr);
        return 0;
    }
#endif
    argc = lua_gettop(tolua_S)-1;
    if (argc == 1) 
    {
        std::function arg0;
        //获取参数
        LUA_FUNCTION handler = (toluafix_ref_function(tolua_S, 2, 0));

        //调用成员函数
        cobj->setCallBack([=](const char* str) {
            LuaStack* stack = LuaEngine::getInstance()->getLuaStack();
            stack->pushString(str);
            stack->executeFunctionByHandler(handler, 1);
            stack->clean();
        });
        lua_settop(tolua_S, 1);
        return 1;
    }
    luaL_error(tolua_S, "%s has wrong number of arguments: %d, was expecting %d \n", "MyClass:setCallBack",argc, 1);
    return 0;
#if COCOS2D_DEBUG >= 1
    tolua_lerror:
    tolua_error(tolua_S,"#ferror in function 'lua_my_class_MyClass_setCallBack'.",&tolua_err);
#endif
    return 0;
}

绑定流程主要也是这三步：

• 获取c++对象
• 获取参数, 校验参数类型
• 调用成员函数

调用成员函数的时候，用到了Lambda表达式。这个不太熟，需要恶补一下。先挖个坑
然后就是Lua跟C++调用的时候内存原理，也需要深入了解。