Why does OracleParameter implement ICloneable but doesn't provide Clone()?

Question

I am using the OracleClient library version 1.0.5000.0 and I am confused about the OracleParameter class and its implementation of ICloneable.

This is the definition of the OracleParameter class:

public sealed class OracleParameter : MarshalByRefObject, IDbDataParameter, IDataParameter, ICloneable {
 public OracleParameter();
 public OracleParameter(string name, object value);
 public OracleParameter(string name, OracleType oracleType);
 public OracleParameter(string name, OracleType oracleType, int size);
 public OracleParameter(string name, OracleType oracleType, int size, string srcColumn);
 public OracleParameter(string name, OracleType oracleType, int size, ParameterDirection direction, bool isNullable, byte precision, byte scale, string srcColumn, DataRowVersion srcVersion, object value);

 [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
 [RefreshProperties(RefreshProperties.All)]
 [Browsable(false)]
 public DbType DbType { get; set; }
 [RefreshProperties(RefreshProperties.All)]
 public ParameterDirection Direction { get; set; }
 [Browsable(false)]
 [DesignOnly(true)]
 [EditorBrowsable(EditorBrowsableState.Never)]
 [DefaultValue(false)]
 public bool IsNullable { get; set; }
 [DefaultValue(0)]
 [Browsable(false)]
 public int Offset { get; set; }
 [RefreshProperties(RefreshProperties.All)]
 public OracleType OracleType { get; set; }
 [DefaultValue("")]
 public string ParameterName { get; set; }
 [DefaultValue(0)]
 public byte Precision { get; set; }
 [DefaultValue(0)]
 public byte Scale { get; set; }
 [DefaultValue(0)]
 public int Size { get; set; }
 [DefaultValue("")]
 public string SourceColumn { get; set; }
 public DataRowVersion SourceVersion { get; set; }
 [DefaultValue("")]
 [RefreshProperties(RefreshProperties.All)]
 [TypeConverter(typeof(StringConverter))]
 public object Value { get; set; }

 public override string ToString();
}

It implements System.ICloneable, but there is no Clone() method in there.

Can anyone explain this?

Answer 1

In .NET you can explicitly implement interface members by using the following syntax:

object System.IClonable.Clone() { }

As a result you can only use the method by explicitly casting to the expected interface.

Also see http://msdn.microsoft.com/en-us/library/system.data.oracleclient.oracleparameter.system.icloneable.clone%28VS.85%29.aspx

Answer 2

This comes up from time to time. :) Check out the following ...

void Main()
{
    var e = new Example();
    I   i = e as I;

    e.m1();  // prints Class m1()
    i.m1();  // prints Interface m1()
}

public interface I
{
  void m1();
}

public class Example : I
{
  public void m1()
  {
    Console.WriteLine( "Class m1()" );
  }

  void I.m1()
  {
    Console.WriteLine( "Interface m1()" );
  }
}