в 15:31, 26 мая 2010

2010-05-26T15:31:53Z

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2010-05-26T12:14:30Z

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==Load class method by Attribute==

<source lang="csharp">using System;
using System.Reflection;
[AttributeUsage(AttributeTargets.Class)]
public class ClassTarget : Attribute
{
public ClassTarget()
{
}
}
[AttributeUsage(AttributeTargets.Method )]
public class MethodTarget : Attribute
{
public MethodTarget()
{
}
}
public class MyClass
{
[MethodTarget]
public int MyMethod()
{
return 5;
}
}

class MainClass
{
public static void Main(string[] args)
{
ClassTarget rs;
MethodTarget rm;
Assembly a = Assembly.LoadFrom("MyClass");
foreach(Type t in a.GetTypes())
{
rs = (ClassTarget) Attribute.GetCustomAttribute(t, typeof(ClassTarget));
if(rs != null)
{
foreach(MethodInfo m in t.GetMethods())
{
rm = (MethodTarget) Attribute.GetCustomAttribute(m, typeof(MethodTarget));
if(rm != null)
{
Object o = Activator.CreateInstance(t);
Object[] aa = new Object[0];
int i = (int) m.Invoke(o, aa);
}
}
}
}

}
}</source>

==Reflecting on Attributes==

<source lang="csharp">//Code revised from
//A Programmer"s Introduction to C# 2.0, Third Edition
using System;
using System.Reflection;
[AttributeUsage(AttributeTargets.Class, AllowMultiple=true)]
public class CodeReviewAttribute: System.Attribute
{
public CodeReviewAttribute(string reviewer, string date)
{
this.reviewer = reviewer;
this.date = date;
}
public string Comment
{
get
{
return(comment);
}
set
{
comment = value;
}
}
public string Date
{
get
{
return(date);
}
}
public string Reviewer
{
get
{
return(reviewer);
}
}
string reviewer;
string date;
string comment;
}
[CodeReview("Name1", "01-12-2000", Comment="comment1")]
[CodeReview("Name2", "01-01-2012", Comment="comment2")]
class Complex
{
}
class MainClass
{
public static void Main()
{
Type type = typeof(Complex);
foreach (CodeReviewAttribute att in
type.GetCustomAttributes(typeof(CodeReviewAttribute), false))
{
Console.WriteLine("Reviewer: {0}", att.Reviewer);
Console.WriteLine("Date: {0}", att.Date);
Console.WriteLine("Comment: {0}", att.rument);
}
}
}</source>
<pre class=codeResult>Reviewer: Name2
Date: 01-01-2012
Comment: comment2
Reviewer: Name1
Date: 01-12-2000
Comment: comment1</pre>

==Retrieve Attribute by using reflection==

<source lang="csharp">using System;
using System.Reflection;

[AttributeUsage(AttributeTargets.All)]
public class MyAttribute : Attribute {
public string remark;

public MyAttribute(string comment) {
remark = comment;
}

public string Remark {
get {
return remark;
}
}
}

[MyAttribute("This class uses an attribute.")]
class UseAttrib {
}

class MainClass {
public static void Main() {
Type t = typeof(UseAttrib);

Console.Write("Attributes in " + t.Name + ": ");

object[] attribs = t.GetCustomAttributes(false);
foreach(object o in attribs) {
Console.WriteLine(o);
}

Console.Write("Remark: ");

// Retrieve the MyAttribute.
Type tRemAtt = typeof(MyAttribute);
MyAttribute ra = (MyAttribute)
Attribute.GetCustomAttribute(t, tRemAtt);

Console.WriteLine(ra.remark);
}
}</source>
<pre class=codeResult>Attributes in UseAttrib: MyAttribute
Remark: This class uses an attribute.</pre>

==Use Reflection to get the Attribute==

<source lang="csharp">using System;
[assembly:System.CLSCompliantAttribute(true)]
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct)]
public class MyDescriptionAttribute : System.Attribute
{
private string description;
public string Desc
{
get { return description; }
set { description = value; }
}
public MyDescriptionAttribute() {}
public MyDescriptionAttribute(string desc)
{ description = desc;}
}

[MyDescriptionAttribute("Info")]
public class MyClass
{
public MyClass()
{
}
}

public class MainClass
{
public static int Main(string[] args)
{
Type t = typeof(MyClass);

// Get all attributes in the assembly.
object[] customAtts = t.GetCustomAttributes(false);

// List all info.
Console.WriteLine("Value of MyDescriptionAttribute");
foreach(MyDescriptionAttribute v in customAtts)
Console.WriteLine("-> {0}\n", v.Desc);
return 0;
}
}</source>
<pre class=codeResult>Value of MyDescriptionAttribute
-> Info</pre>

==Use the GetCustomAttributes method==

<source lang="csharp">using System;
public class TrueFalseAttribute : Attribute
{
bool bWritten;
public bool Written()
{
return bWritten;
}
public TrueFalseAttribute(bool Written)
{
bWritten = Written;
}
}
public class StringAttribute : Attribute
{
string sStage;
public string Stage()
{
return sStage;
}
public StringAttribute(string Stage)
{
sStage = Stage;
}
}
[TrueFalseAttribute(true)]
[StringAttribute("Coding")]
public class Class1
{
}
class MainClass
{
public static void Main()
{
Console.WriteLine("Class1 attributes: ");object[] aAttributes = Attribute.GetCustomAttributes(typeof(Class1));
foreach (object attr in aAttributes)
{
Console.WriteLine(attr);
}
}
}</source>
<pre class=codeResult>Class1 attributes:
StringAttribute
TrueFalseAttribute</pre>

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в 15:31, 26 мая 2010

Admin: 1 версия