C# 0 The Complete Reference

Supplement

 is a public field of 

RemarkAttribute

, it can be used as a named parameter, 

as shown here:

[RemarkAttribute("This class uses an attribute.",

        Supplement = "This is additional info.")]

class UseAttrib {

  // ...

}

Pay close attention to the way 

RemarkAttribute

’s constructor is called. First, the 

positional argument is specified as it was before. Next is a comma, followed by the named 

parameter, 

Supplement

, which is assigned a value. Finally, the closing 

)

 ends the call to the 

constructor. Thus, the named parameter is initialized within the call to the constructor. This 

syntax can be generalized. Position parameters must be specified in the order in which they 

appear. Named parameters are specified by assigning values to their name.

Here is a program that demonstrates the 

Supplement

 field:

// Use a named attribute parameter.

using System;

using System.Reflection;

[AttributeUsage(AttributeTargets.All)]

public class RemarkAttribute : Attribute {

  string pri_remark; // underlies Remark property

  public string Supplement; // this is a named parameter

  public RemarkAttribute(string comment) {

    pri_remark = comment;

    Supplement = "None";

  }

  public string Remark {

    get {

      return pri_remark;

    }

  }

}

[RemarkAttribute("This class uses an attribute.",

                 Supplement = "This is additional info.")]

class UseAttrib {

  // ...

}

class NamedParamDemo {

  static void Main() {

    Type t = typeof(UseAttrib);

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

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