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EvidenceBase Class

Provides a base class from which all objects to be used as evidence must derive.


Namespace:  System.Security.Policy
Assembly:  mscorlib (in mscorlib.dll)

public abstract class EvidenceBase

The EvidenceBase type exposes the following members.

Protected methodEvidenceBaseInitializes a new instance of the EvidenceBase class.

Public methodCloneCreates a new object that is a complete copy of the current instance.
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)

Before the .NET Framework version 4, almost any object could be used as an evidence object if the hosting code wanted to apply it as evidence. For example, some .NET Framework code recognized System.Uri objects as evidence. The common language runtime (CLR) considered evidence objects as System.Object references, and did not apply any type safety to them.

This presented a problem because there were implicit restrictions on which types could be used as evidence objects. Specifically, any object used as evidence had to be serializable and could not be null. If these requirements were not met, the CLR threw an exception whenever an operation that required one of these assumptions was performed.

The EvidenceBase class, which all evidence objects must derive from, was introduced in the .NET Framework 4 to enable constraints on the types of objects that can be used as evidence and to provide the ability to add new features and requirements to all evidence objects. The EvidenceBase class ensures, upon instantiation, that the evidence object is serializable. In addition, it enables new evidence requirements to be created by adding new default implementations to the base class.

All the types used by the CLR as evidence objects have been updated in the .NET Framework 4 to derive from EvidenceBase.

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.