Lua实现事件派发器（转）

转自：http://www.cppblog.com/sunicdavy/archive/2013/04/24/199692.html?opt=admin

之前想把在unity用c#实现的事件系统转到lua上实现，一搜，果然也有人实现了，那就直接拿来用了，也谢谢上面这篇博主的分享。

local Global = _G
local package = _G.package
local setmetatable = _G.setmetatable
local assert = _G.assert
local table = _G.table
local pairs = _G.pairs
local ipairs = _G.ipairs


module "EventDispatcher"

--[[
数据层次

[EventName1] =
{
    [_StaticFunc] = { Func1, Func2 },

    [Object1] = { Func1, Func2 },
    [Object2] = { Func1, Func2 },
},

[EventName2] =
{
    ...
}

]]

-- 默认调用函数
local function PreInvoke( EventName, Func, Object, UserData, ... )

    if Object then
        Func( Object, EventName, ... )
    else
        Func( EventName, ... )
    end

end

function New( )

    local NewObj = setmetatable( {}, { __index = package.loaded["EventDispatcher"] } )

    -- 对象成员初始化
    NewObj.mPreInvokeFunc = PreInvoke
    NewObj.mEventTable = {}

    return NewObj
end

-- 添加
function Add( Self, EventName, Func, Object, UserData )

    assert( Func )

     Self.mEventTable[ EventName ] = Self.mEventTable[ EventName ] or {}

    local Event = Self.mEventTable[ EventName ]

    if not Object then
        Object = "_StaticFunc"
    end

    Event[Object] = Event[Object] or {}
    local ObjectEvent = Event[Object]

    ObjectEvent[Func] = UserData or true

end

-- 设置调用前回调
function SetDispatchHook( Self, HookFunc )

    Self.mPreInvokeFunc = HookFunc
end


-- 派发
function Dispatch( Self, EventName, ... )

    assert( EventName )

    local Event = Self.mEventTable[ EventName ]

    for Object,ObjectFunc in pairs( Event ) do

        if Object == "_StaticFunc" then

            for Func, UserData in pairs( ObjectFunc ) do
                Self.mPreInvokeFunc( EventName, Func, nil, UserData, ... )
            end

        else

            for Func, UserData in pairs( ObjectFunc ) do
                Self.mPreInvokeFunc( EventName, Func, Object, UserData, ... )
            end

        end

    end

end

-- 回调是否存在
function Exist( Self, EventName )

    assert( EventName )

    local Event = Self.mEventTable[ EventName ]

    if not Event then
        return false
    end

    -- 需要遍历下map, 可能有事件名存在, 但是没有任何回调的
    for Object,ObjectFunc in pairs( Event ) do

        for Func, _ in pairs( ObjectFunc ) do
            -- 居然有一个
            return true
        end

    end


    return false

end

-- 清除
function Remove( Self, EventName, Func, Object )

    assert( Func )

    local Event = Self.mEventTable[ EventName ]

    if not Event then
        return
    end

    if not Object then
        Object = "_StaticFunc"
    end


    local ObjectEvent = Event[Object]

    if not ObjectEvent then
        return
    end

    ObjectEvent[Func] = nil


end

-- 清除对象的所有回调
function RemoveObjectAllFunc( Self, EventName, Object )

    assert( Object )

    local Event = Self.mEventTable[ EventName ]

    if not Event then
        return
    end

    Event[Object] = nil

end

用例：

local EventDispatcher = require 'EventDispatcher'
 
local E = EventDispatcher.New()
 
 
E:Add( "a", function( a, b )   print( a, b ) end )
 
local Func = function( a )   print( a ) end 
E:Add( "a", Func )
 
 
E:Dispatch("a", 1, 2 )
print( E:Exist("a"), E:Exist("b"))
 
E:Remove("a", Func )
 
E:Dispatch("a", 1, 2 )
print( E:Exist("a"), E:Exist("b"))

结语：发现lua真的很好用，用得好也很强大，将c#的东西用lua实现一遍的时候发现代码量少了很多。