CA1065: Do not raise exceptions in unexpected locations

Properties are basically smart fields. Therefore, they should behave like a field as much as possible. Fields do not throw exceptions and neither should properties. If you have a property that throws an exception, consider making it a method.

The following exceptions are allowed to be thrown from a property get method:

• System.InvalidOperationException and all derivatives (including System.ObjectDisposedException)

• System.NotSupportedException and all derivatives

• System.ArgumentException (only from indexed get)

• KeyNotFoundException (only from indexed get)

Event accessors should be simple operations that do not throw exceptions. An event should not throw an exception when you try to add or remove an event handler.

The following exceptions are allowed to be thrown from an event accesor:

• System.InvalidOperationException and all derivatives (including System.ObjectDisposedException)

• System.NotSupportedException and all derivatives

• ArgumentException and derivatives

The following Equals methods should not throw exceptions:

• Object.Equals

• M:IEquatable.Equals

An Equals method should return true or false instead of throwing an exception. For example, if Equals is passed two mismatched types it should just return false instead of throwing an ArgumentException.

The following GetHashCode methods should usually not throw exceptions:

• GetHashCode

• M:IEqualityComparer.GetHashCode(T)

GetHashCode should always return a value. Otherwise, you can lose items in the hash table.

The versions of GetHashCode that take an argument can throw an ArgumentException. However, Object.GetHashCode should never throw an exception.

The debugger uses Object.ToString to help display information about objects in string format. Therefore, ToString should not change the state of an object and it should not throw exceptions.

Throwing exceptions from a static constructor causes the type to be unusable in the current application domain. You should have a very good reason (such as a security issue) for throwing an exception from a static constructor.

Throwing an exception from a finalizer causes the CLR to fail fast, which tears down the process. Therefore, throwing exceptions in a finalizer should always be avoided.

A IDisposable.Dispose method should not throw an exception. Dispose is often called as part of the clean up logic in a finally clause. Therefore, explicitly throwing an exception from Dispose forces the user to add exception handling inside the finally clause.

The Dispose(false) code path should never throw exceptions, because this is almost always called from a finalizer.

Like Equals methods, equality operators should return either true or false and should not throw exceptions.

Because the user is often unaware that an implicit cast operator has been called, an exception thrown by the implicit cast operator is completely unexpected. Therefore, no exceptions should be thrown from implicit cast operators.