The attribute of C # syntax

In C #, you define a member of a class, and you can define a property called an attribute. Attribute is called an attribute.

In the FCL, there are built-in attribute. such as:

Condition [Attribute]: In what conditions can be called. (can only be used on methods that return a value of void)

Obsolete: Method deprecated. Support disabled.

Code Listing 1:

classProgram {Static voidMain (string[] args)            {Func ();        Console.ReadLine (); } [Obsolete ("You can use Func -to-replace this",true)]        Private Static voidTest () {Console.WriteLine ("noooo"); }        Private Static voidFunc () {Console.WriteLine ("yesss"); }    }    classT {[Conditional ("DEBUG")]         Public Static voidMstringstr) {Console.WriteLine ("method{0}", str); }    }

built-in attribute

custom Attribute:

Code Listing 2:

[AttributeUsage (attributetargets.class, AllowMultiple =false, inherited =false)]     Public classHelpattribute:attribute { PublicHelpAttribute (stringstr) {Helpstr=str; }         Public stringName {Get;Set; }  Public stringHELPSTR {Get;Set; } }

Custom Attribute

AttributeTargets.Class: The action target can only be a class.

AllowMultiple: Whether the attribute can be multiple-acting on an element.

Inherited: Whether the attribute also inherits when the target is inherited.

Reflection Gets the attribute information for the class :

Code Listing 3:

classProgram {Static voidMain (string[] args) {            varAttrs =typeof(MyClass). GetCustomAttributes (false);  for(inti =0; I < Attrs. Length; i++)            {                varattr = Attrs[i] asHelpAttribute; if(attr! =NULL) Console.WriteLine (attr. Helpstr +attr.            Name);        } console.readline (); }} [Help ("Good", Name ="class")]    classMyClass {}

Reflection Get Property information

The attribute of C # syntax