// Snippet shows how interfaces and coclasses can adorn the Guid attribute.
// Running the regasm will generate .reg and .tlb files. Reg file can be
// used to register the interface and coclass with the registry. Tlb file
// are used to do interop. Also illustrates how System.Guid can be constructed
// and how guid objects can be compared.
namespace GuidSnippet
{
//
using System;
using System.Runtime.InteropServices;
// Guid for the interface IFoo.
[Guid("F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4")]
interface IFoo
{
void Foo();
}
// Guid for the coclass CFoo.
[Guid("936DA01F-9ABD-4d9d-80C7-02AF85C822A8")]
public class CFoo : IFoo
{
// Run regasm on this assembly to create .reg and .tlb files.
// Reg file can be used to register this coclass in the registry.
// Tlb file will be used to do interop.
public void Foo() {}
public static void Main( string []args )
{
// Snippet addresses the following in System.Runtime.InterOpServices.GuidAttribute.
// How to specify the attribute on interface/coclass.
// Retrieve the GuidAttribute from an interface/coclass.
// Value property on GuidAttribute class.
// Snippet addresses the following in System.Guid.
// Constructor Guid(string).
// Constructor Guid(ByteArray).
// Equals.
// Operator ==.
// CompareTo.
Attribute IFooAttribute = Attribute.GetCustomAttribute( typeof( IFoo ), typeof( GuidAttribute ) );
// The Value property of GuidAttribute returns a string.
System.Console.WriteLine( "IFoo Attribute: " + ((GuidAttribute)IFooAttribute).Value );
// Using the string to create a guid.
Guid guidFoo1 = new Guid( ((GuidAttribute)IFooAttribute).Value );
// Using a byte array to create a guid.
Guid guidFoo2 = new Guid ( guidFoo1.ToByteArray() );
// Equals is overriden and so value comparison is done though references are different.
if ( guidFoo1.Equals( guidFoo2 ) )
System.Console.WriteLine( "guidFoo1 equals guidFoo2" );
else
System.Console.WriteLine( "guidFoo1 not equals guidFoo2" );
// Equality operator can also be used to determine if two guids have same value.
if ( guidFoo1 == guidFoo2 )
System.Console.WriteLine( "guidFoo1 == guidFoo2" );
else
System.Console.WriteLine( "guidFoo1 != guidFoo2" );
// CompareTo returns 0 if the guids have same value.
if ( guidFoo1.CompareTo( guidFoo2 ) == 0 )
System.Console.WriteLine( "guidFoo1 compares to guidFoo2" );
else
System.Console.WriteLine( "guidFoo1 does not compare to guidFoo2" );
System.Console.ReadLine();
//Output.
//IFoo Attribute: F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4
//guidFoo1 equals guidFoo2
//guidFoo1 == guidFoo2
//guidFoo1 compares to guidFoo2
}
}
}