一个ASP创建动态对象的工厂类（类似PHP的stdClass）


            最近整理ASP/VBScript代码，发现过去的一个ASP实现的MVC框架，可惜是个半成品，效率也成问题，不过发现里面有些我写的代码，感觉还稍稍可以拿出来见人，于是今天作此文以记之。

说是ASP，其实和VBScript也脱不了干系，VBScript语言传承于Visual Basic，VB的语法灵活度已经不尽如人意了，VBS作为其子集可想而知。神马反射、自省等先进的技术，微软在.NET中才引入。作为被抛弃的技术，也不奢望微软能够提供支持，于是顽固守旧的程序员只有绞尽脑汁的去模仿实现一些类似的功能。

好吧，我承认很长一段时间我就是顽固守旧派中的一员，今天介绍的就是其中的一项功能，动态创建一个属性对象，属性对象姑且这么称呼，也就是说动态创建的对象只包含属性(Properties)。

下面贴出实现代码供大家参考：

复制代码 代码如下:'' ASP/VBScript Dynamic Object Generator' Author: WangYe' For more information please visit'     ' This code is distributed under the BSD license'Const PROPERTY_ACCESS_READONLY = 1Const PROPERTY_ACCESS_WRITEONLY = -1Const PROPERTY_ACCESS_ALL = 0Class DynamicObject    Private m_objProperties    Private m_strName    Private Sub Class_Initialize()        Set m_objProperties = CreateObject("Scripting.Dictionary")        m_strName = "AnonymousObject"    End Sub    Private Sub Class_Terminate()        If Not IsObject(m_objProperties) Then            m_objProperties.RemoveAll        End If        Set m_objProperties = Nothing    End Sub    Public Sub setClassName(strName)        m_strName = strName    End Sub    Public Sub add(key, value, access)        m_objProperties.Add key, Array(value, access)    End Sub    Public Sub setValue(key, value, access)        If m_objProperties.Exists(key) Then            m_objProperties.Item(key)(0) = value            m_objProperties.Item(key)(1) = access        Else            add key,value,access        End If    End Sub    Private Function getReadOnlyCode(strKey)        Dim strPrivateName, strPublicGetName        strPrivateName = "m_var" & strKey        strPublicGetName = "get" & strKey        getReadOnlyCode = _            "Public Function " & strPublicGetName & "() :" & _            strPublicGetName & "=" & strPrivateName & " : " & _            "End Function : Public Property Get " & strKey & _            " : " & strKey & "=" & strPrivateName & " : End Property : "    End Function    Private Function getWriteOnlyCode(strKey)        Dim pstr        Dim strPrivateName, strPublicSetName, strParamName        strPrivateName = "m_var" & strKey        strPublicSetName = "set" & strKey        strParamName = "param" & strKey        getWriteOnlyCode = _            "Public Sub " & strPublicSetName & "(" & strParamName & ") :" & _            strPrivateName & "=" & strParamName & " : " & _            "End Sub : Public Property Let " & strKey & "(" & strParamName & ")" & _            " : " & strPrivateName & "=" & strParamName & " : End Property : "    End Function    Private Function parse()        Dim i, Keys, Items        Keys = m_objProperties.Keys        Items = m_objProperties.Items        Dim init, pstr        init = ""        pstr = ""        parse = "Class " & m_strName & " :" & _                "Private Sub Class_Initialize() : "        Dim strPrivateName        For i = 0 To m_objProperties.Count - 1            strPrivateName = "m_var" & Keys(i)            init = init & strPrivateName & "=""" & _                Replace(CStr(Items(i)(0)), """", """""") & """:"            pstr = pstr & "Private " & strPrivateName & " : "            If CInt(Items(i)(1)) > 0 Then ' ReadOnly                pstr = pstr & getReadOnlyCode(Keys(i))            ElseIf CInt(Items(i)(1)) < 0 Then ' WriteOnly                pstr = pstr & getWriteOnlyCode(Keys(i))            Else ' AccessAll                pstr = pstr & getReadOnlyCode(Keys(i)) & _                        getWriteOnlyCode(Keys(i))            End If        Next        parse = parse & init & "End Sub : " &  pstr & "End Class"    End Function    Public Function getObject()        Call Execute(parse)        Set getObject = Eval("New " & m_strName)    End Function    Public Sub invokeObject(ByRef obj)        Call Execute(parse)        Set obj = Eval("New " & m_strName)    End SubEnd Class

对于属性对象分别提供了Property直接访问模式和set或者get函数访问模式，当然我还提供了三种权限控制，在add方法中使用，分别是PROPERTY_ACCESS_READONLY（属性只读）、PROPERTY_ACCESS_WRITEONLY（属性只写）和PROPERTY_ACCESS_ALL（属性读写），你可以像下面这样使用（一个例子）：复制代码 代码如下:Dim DynObjSet DynObj = New DynamicObject    DynObj.add "Name", "WangYe", PROPERTY_ACCESS_READONLY    DynObj.add "HomePage", "http://zwyuanma.com", PROPERTY_ACCESS_READONLY    DynObj.add "Job", "Programmer", PROPERTY_ACCESS_ALL    '    ' 如果没有setClassName，    ' 新创建的对象将会自动命名为AnonymousObject    ' 但是如果创建多个对象，就必须指定名称    ' 否则就可能引起对象名重复的异常    DynObj.setClassName "User"    Dim User    Set User = DynObj.GetObject()    ' 或者 DynObj.invokeObject User        Response.Write User.Name        ' Response.Write User.getName() Response.Write User.HomePage        ' Response.Write User.getHomePage() Response.Write User.Job        ' Response.Write User.getJob()

        ' 改变属性值        User.Job = "Engineer"        ' User.setJob "Engineer"

        Response.Write User.getJob()    Set User = NothingSet DynObj = Nothing其原理很简单，就是通过给定的Key-Value动态生成VBS Class脚本代码，然后调用Execute执行以便于将这段代码加入到代码上下文流中，最后再通过Eval新建这个对象。

好了，就介绍到这里，今后我可能还会陆续公开一些Classic ASP的相关技巧代码。

2012年11月7日更新

修复从旧项目移植过来导致的BUG。

修复了一些Bug增加了一些特性，我先把最新的代码贴出来供大家参考：

复制代码 代码如下:'' ASP/VBScript Dynamic Object Generator' Author: WangYe' For more information please visit'     ' This code is distributed under the BSD license'' UPDATE:'   2012/11/7'       1. Add variable key validator.'       2. Add hasattr_ property for determine'          if the property exists.'       3. Add getattr_ property for get property'          value safety.'       4. Class name can be accessed by ClassName_ property.'       5. Fixed some issues.'Const PROPERTY_ACCESS_READONLY = 1Const PROPERTY_ACCESS_WRITEONLY = -1Const PROPERTY_ACCESS_ALL = 0Class DynamicObject    Private m_objProperties    Private m_strName    Private m_objRegExp    Private Sub Class_Initialize()        Set m_objProperties = CreateObject("Scripting.Dictionary")        Set m_objRegExp = New RegExp            m_objRegExp.IgnoreCase = True            m_objRegExp.Global = False            m_objRegExp.Pattern = "^[a-z][a-z0-9]*$"        m_strName = "AnonymousObject"        m_objProperties.Add "ClassName_", _            Array(m_strName, PROPERTY_ACCESS_READONLY)    End Sub    Private Sub Class_Terminate()        Set m_objRegExp = Nothing        If IsObject(m_objProperties) Then            m_objProperties.RemoveAll        End If        Set m_objProperties = Nothing    End Sub    Public Sub setClassName(strName)        If Not m_objRegExp.Test(strName) Then            ' Skipped Invalid Class Name            ' Raise            Exit Sub        End If        m_strName = strName        m_objProperties("ClassName_") = _            Array(m_strName, PROPERTY_ACCESS_READONLY)    End Sub    Public Sub add(key, value, access)        If Not m_objRegExp.Test(key) Then            ' Skipped Invalid key            ' Raise            Exit Sub        End If        If key = "hasattr_" Then key = "hasattr__"        If key = "ClassName_" Then key = "ClassName__"        'Response.Write key        m_objProperties.Add key, Array(value, access)    End Sub    Public Sub setValue(key, value, access)        If m_objProperties.Exists(key) Then            m_objProperties.Item(key)(0) = value            m_objProperties.Item(key)(1) = access        Else            add key,value,access        End If    End Sub    Private Function getReadOnlyCode(strKey)        Dim strPrivateName, strPublicGetName        strPrivateName = "m_var" & strKey        strPublicGetName = "get" & strKey        getReadOnlyCode = _            "Public Function " & strPublicGetName & "() :" & _            strPublicGetName & "=" & strPrivateName & " : " & _            "End Function : Public Property Get " & strKey & _            " : " & strKey & "=" & strPrivateName & _            " : End Property : "    End Function    Private Function getWriteOnlyCode(strKey)        Dim pstr        Dim strPrivateName, strPublicSetName, strParamName        strPrivateName = "m_var" & strKey        strPublicSetName = "set" & strKey        strParamName = "param" & strKey        getWriteOnlyCode = _            "Public Sub " & strPublicSetName & _            "(" & strParamName & ") :" & _            strPrivateName & "=" & strParamName & " : " & _            "End Sub : Public Property Let " & strKey & _            "(" & strParamName & ")" & _            " : " & strPrivateName & "=" & strParamName & _            " : End Property : "    End Function    Private Function parse()        Dim i, Keys, Items        Keys = m_objProperties.Keys        Items = m_objProperties.Items        Dim init, pstr        init = ""        pstr = ""        parse = "Class " & m_strName & " :" & _                "Private Sub Class_Initialize() : "        Dim strPrivateName, strAvailableKeys        For i = 0 To m_objProperties.Count - 1            strPrivateName = "m_var" & Keys(i)            init = init & strPrivateName & "=""" & _                Replace(CStr(Items(i)(0)), """", """""") & """:"            pstr = pstr & "Private " & strPrivateName & " : "            strAvailableKeys = strAvailableKeys & Keys(i) & ","            If CInt(Items(i)(1)) > 0 Then ' ReadOnly                pstr = pstr & getReadOnlyCode(Keys(i))            ElseIf CInt(Items(i)(1)) < 0 Then ' WriteOnly                pstr = pstr & getWriteOnlyCode(Keys(i))            Else ' AccessAll                pstr = pstr & getReadOnlyCode(Keys(i)) & _                        getWriteOnlyCode(Keys(i))            End If        Next        init = init & "m_strAvailableKeys = Replace(""," & _                strAvailableKeys & """, "" "", """") : "        Dim hasstmt        hasstmt = "Private m_strAvailableKeys : " & _                  "Public Function hasattr_(ByVal key) : " & _                  "hasattr_ = CBool(InStr(m_strAvailableKeys," & _                  " "","" & key & "","") > 0) : " & _                  "End Function : " & _                  "Public Function getattr_(ByVal key, ByVal defaultValue) : " & _                  "If hasattr_(key) Then : getattr_ = Eval(key) : " & _                  "Else : getattr_ = defaultValue : End If : " & _                  "End Function : "        parse = parse & init & "End Sub : " & _            hasstmt & pstr & "End Class"    End Function    Public Function getObject()        'Response.Write parse        Call Execute(parse)        Set getObject = Eval("New " & m_strName)    End Function    Public Sub invokeObject(ByRef obj)        Call Execute(parse)        Set obj = Eval("New " & m_strName)    End SubEnd Class

需要注意的几个新特性：

1. 增加了类名和属性名验证措施，防止畸形的类名或者属性名导致动态生成的代码出现语法错误。不过处理的方式是直接忽略，本来想Raise异常的，但考虑到VBS对异常处理不是很好的，所以采取忽略策略：

' 有效的类名或属性名必须以字母开头复制代码 代码如下:Dim DynObjSet DynObj = New DynamicObject    DynObj.setClassName "1User" ' 此句将被忽略，因为类名不能以数字开始    ' 下面这句也会被忽略，因为属性名不能以特殊符号开始    DynObj.add "%Name", "WangYe", PROPERTY_ACCESS_READONLYSet DynObj = Nothing2. 对于动态对象增加了hasattr_方法，该属性用于检测此对象是否支持相应的属性，可以在访问一个属性前先确定该对象是否支持此属性：复制代码 代码如下:Dim DynObjSet DynObj = New DynamicObject    DynObj.add "Name", "WangYe", PROPERTY_ACCESS_READONLY    Response.Write DynObj.hasattr_("Name") ' True    Response.Write DynObj.hasattr_("Favor") ' False

Set DynObj = Nothing

3. 对于动态对象增加了getattr_方法，此方法可以安全的获取指定的属性值，避免因为对象不存在属性值导致出错。方法原型为getattr_(ByVal propertyName, ByVal defaultValue)，参数propertyName指定属性的名字，defaultValue是当指定属性不存在是可以返回的默认值，比如下面代码：复制代码 代码如下:Dim DynObjSet DynObj = New DynamicObject    DynObj.add "Name", "WangYe", PROPERTY_ACCESS_READONLY    Response.Write DynObj.getattr_("Name", "N/A") ' WangYe    Response.Write DynObj.getattr_("Favor", "N/A") ' N/A

Set DynObj = Nothing4. 动态对象的类名可以通过ClassName_属性或者getClassName_()方法获取。

2012年11月12日更新

修复双引号导致构造类错误或导致执行任意代码的Bug。