浅谈Dynamic 关键字系列之三(上):ExpandoObject, DynamicObject, DynamicMetaObject
2011-07-05 19:22
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ExpandoObject:表示一个对象,该对象包含可在运行时动态添加和移除的成员。
dynEO.number 中number是动态添加属性。
dynEO.Increment 中Increment 是动态添加的Action 委托。
枚举ExpandoObject的所有成员:
结果如下:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
接收属性更改的通知:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
结果:
System.Dynamic.DynamicObject:提供用于指定运行时的动态行为的基类
新建类DynamicProduct,基本和Product类似:
可以看到继承了DynamicObject后,可以override 一大堆TryXXX的方法了。
重点需要了解的是:
完整的代码如下:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
Main函数代码如下:
结果如下:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
理论上来说,应该输出:
TrySetMember :设置name字段
TrySetMember :设置Id属性
TryGetMember :获取Id属性
TrySetMember :设置Id属性
TryInvokeMember :调用ShowProduct方法
Id =4 ,Name = n1
为什么TryXXX方法没有被调用??
下篇将解释这个问题,请持续关注..
dynamic dynEO = new ExpandoObject(); dynEO.number = 10; dynEO.Increment = new Action(() => { dynEO.number++; }); Console.WriteLine(dynEO.number); dynEO.Increment(); Console.WriteLine(dynEO.number);
dynEO.number 中number是动态添加属性。
dynEO.Increment 中Increment 是动态添加的Action 委托。
枚举ExpandoObject的所有成员:
foreach (var property in (IDictionary<String, Object>)dynEO) { Console.WriteLine(property.Key + ": " + property.Value); }
结果如下:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
接收属性更改的通知:
static void Main(string[] args) { ……… ((INotifyPropertyChanged)dynEO).PropertyChanged += new PropertyChangedEventHandler(Program_PropertyChanged); dynEO.Name = "changed"; dynEO.Name = "another"; Console.ReadLine(); } static void Program_PropertyChanged(object sender, PropertyChangedEventArgs e) { Console.WriteLine("属性{0} 已更改", e.PropertyName); }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
结果:
System.Dynamic.DynamicObject:提供用于指定运行时的动态行为的基类
新建类DynamicProduct,基本和Product类似:
可以看到继承了DynamicObject后,可以override 一大堆TryXXX的方法了。
重点需要了解的是:
假设sampleObject 就是dynamicObject | |
TryGetMember | 在调用 int number = sampleObject.Number.时使用 |
TrySetMember | 在调用sampleObject.Number = number 时使用 |
TryInvoke | 在调用sampleObject(100) 时使用 |
TryInvokeMember | 在调用sampleObject.someMethod(100) 时使用 |
完整的代码如下:
class DynamicProduct : DynamicObject { public string name; public int Id { get; set; } public void ShowProduct() { Console.WriteLine("Id={0} ,Name={1}", Id, name); } #region Override DynamicObject 的方法 public override IEnumerable<string> GetDynamicMemberNames() { return base.GetDynamicMemberNames(); } public override bool TryGetMember(GetMemberBinder binder, out object result) { Console.WriteLine("TryGetMember被调用了,Name:{0}", binder.Name); return base.TryGetMember(binder, out result); } public override bool TrySetMember(SetMemberBinder binder, object value) { Console.WriteLine("TrySetMember被调用了,Name:{0}", binder.Name); return base.TrySetMember(binder, value); } public override bool TryInvoke(InvokeBinder binder, object[] args, out object result) { Console.WriteLine("TryInvoke被调用了"); return base.TryInvoke(binder, args, out result); } public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { Console.WriteLine("TryInvokeMember被调用了,Name:{0}", binder.Name); return base.TryInvokeMember(binder, args, out result); } #endregion }
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
Main函数代码如下:
static void Main(string[] args) { dynamic dynProduct = new DynamicProduct(); dynProduct.name = "n1"; //调用TrySetMember方法 dynProduct.Id = 1; dynProduct.Id = dynProduct.Id + 3; dynProduct.ShowProduct(); Console.ReadLine(); }
结果如下:
.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }
理论上来说,应该输出:
TrySetMember :设置name字段
TrySetMember :设置Id属性
TryGetMember :获取Id属性
TrySetMember :设置Id属性
TryInvokeMember :调用ShowProduct方法
Id =4 ,Name = n1
为什么TryXXX方法没有被调用??
下篇将解释这个问题,请持续关注..
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