2014/5/29 记录

1. ExpandoObject   扩展对象,运行时动态添加和移除的成员;  要用dynamic 声明,可以在编译时跳过检查,只打包信息, 在运行时在查查找并执行; 有没有javacript Prototype 的感觉?

http://msdn.microsoft.com/zh-cn/library/system.dynamic.expandoobject.aspx

2.DynamicObject 一个基类, 派生类可以override TryGetMember, TrySetMember, TryInvokeMember/TryInvoke 等方法; 

http://msdn.microsoft.com/zh-cn/library/system.dynamic.dynamicobject(v=vs.110).aspx

其中关于TryInvoke可以细细品味 , 如下:

public class DynamicNumber : DynamicObject
{
    // The inner dictionary to store field names and values.
    Dictionary<string, object> dictionary
        = new Dictionary<string, object>();

    // Get the property value.
    public override bool TryGetMember(
        GetMemberBinder binder, out object result)
    {
        return dictionary.TryGetValue(binder.Name, out result);
    }

    // Set the property value.
    public override bool TrySetMember(
        SetMemberBinder binder, object value)
    {
        dictionary[binder.Name] = value;
        return true;
    }

    // Initializing properties with arguments' values.
    public override bool TryInvoke(
        InvokeBinder binder, object[] args, out object result)
    {
        // The invoke operation in this case takes two arguments.
        // The first one is integer and the second one is string.
        if ((args.Length == 2) &&
            (args[0].GetType() == typeof(int)) &&
            (args[1].GetType() == typeof(String)))
        {
            // If the property already exists, 
            // its value is changed.
            // Otherwise, a new property is created.
            if (dictionary.ContainsKey("Numeric"))
                dictionary["Numeric"] = args[0];
            else
                dictionary.Add("Numeric", args[0]);

            if (dictionary.ContainsKey("Textual"))
                dictionary["Textual"] = args[1];
            else
                dictionary.Add("Textual", args[1]);

            result = true;
            return true;
        }

        else
        {
            // If the number of arguments is wrong,
            // or if arguments are of the wrong type,
            // the method returns false.
            result = false;
            return false;
        }
    }
}
class Program
{
    static void Test(string[] args)
    {
        // Creating a dynamic object.
        dynamic number = new DynamicNumber();

        // Adding and initializing properties.
        // The TrySetMember method is called.
        number.Numeric = 1;
        number.Textual = "One";

        // Printing out the result.
        // The TryGetMember method is called.
        Console.WriteLine(number.Numeric + " " + number.Textual);

        // Invoking an object.
        // The TryInvoke method is called.
        number(2, "Two");
        Console.WriteLine(number.Numeric + " " + number.Textual);

        // The following statement produces a run-time exception
        // because in this example the method invocation 
        // expects two arguments.
        // number(0);
    }
}

// This code example produces the following output:

// 1 One
// 2 Two

3. CallSite & CallSiteBinder

http://msdn.microsoft.com/zh-cn/library/dd402827.aspx

http://msdn.microsoft.com/zh-cn/library/dd728234(v=VS.95)

5. dynamic 反编译后会是什么?

 static void Main() 
        { 
            dynamic d = 5; 
            d.ToString(); 
            d.ToString(); 
        } 

internal class Program 
{ 
    // Methods 
    private static void Main() 
    { 
        object d = 5; 
        if (<Main>o__SiteContainer0.<>p__Site1 == null) 
        { 
            <Main>o__SiteContainer0.<>p__Site1 = CallSite<Action<CallSite, object>>.Create(new CSharpInvokeMemberBinder(CSharpCallFlags.None, "ToString", typeof(Program), null, new CSharpArgumentInfo[] { new CSharpArgumentInfo(CSharpArgumentInfoFlags.None, null) })); 
        } 
        <Main>o__SiteContainer0.<>p__Site1.Target(<Main>o__SiteContainer0.<>p__Site1, d); 
        if (<Main>o__SiteContainer0.<>p__Site2 == null) 
        { 
            <Main>o__SiteContainer0.<>p__Site2 = CallSite<Action<CallSite, object>>.Create(new CSharpInvokeMemberBinder(CSharpCallFlags.None, "ToString", typeof(Program), null, new CSharpArgumentInfo[] { new CSharpArgumentInfo(CSharpArgumentInfoFlags.None, null) })); 
        } 
        <Main>o__SiteContainer0.<>p__Site2.Target(<Main>o__SiteContainer0.<>p__Site2, d); 
    } 

    // Nested Types 
    [CompilerGenerated] 
    private static class <Main>o__SiteContainer0 
    { 
        // Fields 
        public static CallSite<Action<CallSite, object>> <>p__Site1; 
        public static CallSite<Action<CallSite, object>> <>p__Site2; 
    } 
}