ReSharper suggests that the following be changed from:
Type foo = typeof( Foo );
Type bar = typeof( Bar );
if( foo.Equals( bar ) ) { ... }
To:
if( foo == bar ) { ... }
operator ==
// Summary:
// Indicates whether two System.Type objects are equal.
//
// Parameters:
// left:
// The first object to compare.
//
// right:
// The second object to compare.
//
// Returns:
// true if left is equal to right; otherwise, false.
public static bool operator ==( Type left, Type right );
Equals( Type o )
// Summary:
// Determines if the underlying system type of the current System.Type is the
// same as the underlying system type of the specified System.Type.
//
// Parameters:
// o:
// The System.Type whose underlying system type is to be compared with the underlying
// system type of the current System.Type.
//
// Returns:
// true if the underlying system type of o is the same as the underlying system
// type of the current System.Type; otherwise, false.
public virtual bool Equals( Type o );
Question
Why would operator ==
be recommended over Equals( Type o )
when comparing Types?
I suggest that you read the excellent When is a Type not a Type? blog post by Brad Wilson. To summarize: a runtime type (represented by the internal type RuntimeType), managed by the CLR, is not always the same as a Type
, which can be extended. Equals
will check the underlying system type, whereas ==
will check the type itself.
A simple example:
Type type = new TypeDelegator(typeof(int));
Console.WriteLine(type.Equals(typeof(int))); // Prints True
Console.WriteLine(type == typeof(int)); // Prints False