Type System.Security.CodeAccessPermission

extends System.Object

extends System.Security.IPermission

Variables:
Constructors:

protected System.Security.CodeAccessPermission()

Constructs a new instance of the System.Security.CodeAccessPermission class.

Functions:

public System.Void Assert()

Asserts that calling code can access the resource identified by the current instance through the code that calls this method, even if callers have not been granted permission to access the resource.

Throws: : The calling code does not have System.Security.Permissions.SecurityPermissionFlag.Assertion.

Calling System.Security.CodeAccessPermission.Assert stops the permission check on callers that are after the code performing the assert. An assertion is effective only if the code that calls System.Security.CodeAccessPermission.Assert passes the security check for the permission that it is asserting. Even if the callers that are after the code performing the assert do not have the requisite permissions, they can still access resources through the code that calls this method. Because the assertion only applies to the callers of the code performing the assert, a security check for the asserted permission may still fail if the code calling System.Security.CodeAccessPermission.Assert has not itself been granted that permission. A call to System.Security.CodeAccessPermission.Assert is effective until the code containing the call returns to its caller. Caution: Because calling System.Security.CodeAccessPermission.Assert removes the requirement that all code be granted permission to access the specified resource, it can open up security vulnerabilities if used incorrectly or inappropriately.

public System.Security.IPermission Copy()

Returns a System.Security.CodeAccessPermission containing the same values as the current instance.

Returns: A new System.Security.CodeAccessPermission instance that is value equal to the current instance.

This method is implemented to support the System.Security.IPermission interface. The object returned by this method is required be the same type as the current instance and to represent the same access to resources as the current instance. Override this method to create a copy an instance in a type derived from System.Security.CodeAccessPermission. Use this method to obtain a copy of the current instance that has values identical to those of the current instance.

public System.Void Demand()

Forces a System.Security.SecurityException if all callers do not have the permission specified by the current instance.

Throws: : A caller does not have the permission specified by the current instance. A caller has called System.Security.CodeAccessPermission.Deny for the resource protected by the current instance.

The permissions of the code that calls this method are not examined; the check begins from the immediate caller of that code and continues until all callers have been checked, one of the callers invokes System.Security.CodeAccessPermission.Assert , or a caller has been found that is not granted the demanded permission, in which case a System.Security.SecurityException is thrown. System.Security.CodeAccessPermission.Demand is typically used by shared libraries to ensure that callers have permission to access a resource. For example, a method in a shared library calls System.Security.CodeAccessPermission.Demand for the necessary System.Security.Permissions.FileIOPermission before performing a file operation requested by the caller. This method is implemented to support the System.Security.IPermission interface.

public System.Void Deny()

Denies access to the resources specified by the current instance through the code that calls this method.

This method prevents callers from accessing the protected resource through the code that calls this method, even if those callers have been granted permission to access it. The call to System.Security.CodeAccessPermission.Deny is effective until the calling code returns. System.Security.CodeAccessPermission.Deny is ignored for a permission not granted because a demand for that permission will not succeed. System.Security.CodeAccessPermission.Deny can limit the liability of the programmer or prevent accidental security vulnerabilities because it prevents the method that calls System.Security.CodeAccessPermission.Deny from being used to access the resource protected by the denied permission.

public System.Void FromXml(System.Security.SecurityElement elem)

Reconstructs the state of a System.Security.CodeAccessPermission object using the specified XML encoding.

Parameter elem: A System.Security.SecurityElement instance containing the XML encoding to use to reconstruct the state of a System.Security.CodeAccessPermission object.

Throws: : elem does not contain the XML encoding for a instance of the same type as the current instance. The version number of elem is not valid.

The values of the current instance are set to the values of the permission object encoded in elem . Override this method to reconstruct subclasses of System.Security.CodeAccessPermission . This method is called by the system. For the XML encoding for this class, see the System.Security.CodeAccessPermission class page.

public System.Security.IPermission Intersect(System.Security.IPermission target)

Returns a System.Security.CodeAccessPermission object that is the intersection of the current instance and the specified object.

Parameter target: A System.Security.CodeAccessPermission instance to intersect with the current instance.

Returns: A new System.Security.CodeAccessPermission instance that represents the intersection of the current instance and target . If the intersection is empty or target is null, returns null. If the current instance is unrestricted, returns a copy of target. If target is unrestricted, returns a copy of the current instance.

Throws: : target is not null and is not a System.Security.CodeAccessPermission object.

This method is implemented to support the System.Security.IPermission interface. As described above. Override this method to provide a mechanism for creating an intersection of two System.Security.IPermission objects that are of the same type and are derived from System.Security.CodeAccessPermission . The intersection of two permissions is a permission that secures the resources and operations secured by both permissions. Specifically, it represents the minimum permission such that any demand that passes both permissions will also pass their intersection.

public System.Boolean IsSubsetOf(System.Security.IPermission target)

Determines whether the current instance is a subset of the specified object.

Parameter target: A System.Security.CodeAccessPermission instance that is to be tested for the subset relationship.

Returns: true if the current instance is a subset of target; otherwise, false. If the current instance is unrestricted, and target is not, returns false. If target is unrestricted, returns true .

Throws: : target is not null and is not of type System.Security.CodeAccessPermission .

This method is implemented to support the System.Security.IPermission interface. As described above. Override this method to implement the test for the subset relationship in types derived from System.Security.CodeAccessPermission . The current instance is a subset of target if the current instance specifies a set of accesses to resources that is wholly contained by target. For example, a permission that represents read access to a file is a subset of a permission that represents read and write access to the file. If this method returns true , the current instance does not describe a level of access to a set of resources that is not already described by target.

public System.String ToString()

Returns the XML representation of the state of the current instance.

Returns: A System.String containing the XML representation of the state of the current instance.

The XML representation of the current instance is obtained by first calling System.Security.CodeAccessPermission.ToXml, then calling System.Object.ToString on the object returned by that method. This method overrides System.Object.ToString.

public System.Security.SecurityElement ToXml()

Returns the XML encoding of the current instance.

Returns: A System.Security.SecurityElement containing an XML encoding of the state of the current instance.

The object returned by this method is required to use the XML encoding for the System.Security.CodeAccessPermission class as defined on the class page. The state of the current instance is required to be reproducible by invoking System.Security.CodeAccessPermission.FromXml(System.Security.SecurityElement) on an instance of System.Security.CodeAccessPermission using the object returned by this method. Override this method to return an object containing the XML encoding for types derived from System.Security.CodeAccessPermission . This method is called by the system.

public virtual System.Security.IPermission Union(System.Security.IPermission other)

Returns a System.Security.CodeAccessPermission object that is the union of the current instance and the specified object.

Parameter other: A System.Security.IPermission object of the same type as the current instance to be combined with the current instance.

Returns: If other is null, returns a copy of the current instance using the System.Security.IPermission.Copy method.

Throws: : other is not of type System.Security.CodeAccessPermission .

Throws: : other is not null.

This method is implemented to support the System.Security.IPermission interface. This method returns a new System.Security.CodeAccessPermission instance that represents the union of the current instance and other. If the current instance or other is unrestricted, returns a System.Security.CodeAccessPermission instance that is unrestricted. If other is null, returns a copy of the current instance using the System.Security.IPermission.Copy method. If other is not null, this method throws a System.NotSupportedException exception; otherwise, returns a copy of the current instance. Override this method to provide a mechanism for creating the union of two System.Security.IPermission objects that are of the same type and are derived from System.Security.CodeAccessPermission . The result of a call to System.Security.CodeAccessPermission.Union(System.Security.IPermission) is a permission that represents all of the access to resources represented by both the current instance and other . Any demand that passes either permission passes their union.

Functions inherited from System.Object:

public virtual System.Boolean Equals(System.Object obj)

Determines whether the specified System.Object is equal to the current instance.

Parameter obj: The System.Object to compare with the current instance.

Returns: true if obj is equal to the current instance; otherwise, false.

The statements listed below are required to be true for all implementations of the System.Object.Equals(System.Object) method. In the list, x, y, and z represent non-null object references. See System.Object.GetHashCode for additional required behaviors pertaining to the System.Object.Equals(System.Object) method. Implementations of System.Object.Equals(System.Object) should not throw exceptions. The System.Object.Equals(System.Object) method tests for referential equality , which means that System.Object.Equals(System.Object) returns true if the specified instance of Object and the current instance are the same instance; otherwise, it returns false . An implementation of the System.Object.Equals(System.Object) method is shown in the following C# code: public virtual bool Equals(Object obj) { return this == obj; } For some kinds of objects, it is desirable to have System.Object.Equals(System.Object) test for value equality instead of referential equality. Such implementations of Equals return true if the two objects have the same "value", even if they are not the same instance. The definition of what constitutes an object's "value" is up to the implementer of the type, but it is typically some or all of the data stored in the instance variables of the object. For example, the value of a System.String is based on the characters of the string; the Equals method of the System.String class returns true for any two string instances that contain exactly the same characters in the same order. When the Equals method of a base class provides value equality, an override of Equals in a class derived from that base class should invoke the inherited implementation of Equals . It is recommended (but not required) that types overriding System.Object.Equals(System.Object) also override System.Object.GetHashCode. Hashtables cannot be relied on to work correctly if this recommendation is not followed. If your programming language supports operator overloading, and if you choose to overload the equality operator for a given type, that type should override the Equals method. Such implementations of the Equals method should return the same results as the equality operator. Following this guideline will help ensure that class library code using Equals (such as System.Collections.ArrayList and System.Collections.Hashtable ) behaves in a manner that is consistent with the way the equality operator is used by application code. If you are implementing a value type, you should follow these guidelines: For reference types, the guidelines are as follows: If you implement System.IComparable on a given type, you should override Equals on that type. The System.Object.Equals(System.Object) method is called by methods in collections classes that perform search operations, including the System.Array.IndexOf(System.Array,System.Object) method and the System.Collections.ArrayList.Contains(System.Object) method.

Example:

Example 1:

The following example contains two calls to the default implementation of System.Object.Equals(System.Object) .

using System;
class MyClass {
   static void Main() {
      Object obj1 = new Object();
      Object obj2 = new Object();
      Console.WriteLine(obj1.Equals(obj2));
      obj1 = obj2; 
      Console.WriteLine(obj1.Equals(obj2)); 
   }
}

The output is

False

True

Example 2:

The following example shows a Point class that overrides the System.Object.Equals(System.Object) method to provide value equality and a class Point3D, which is derived from Point . Because Point's override of System.Object.Equals(System.Object) is the first in the inheritance chain to introduce value equality, the Equals method of the base class (which is inherited from System.Object and checks for referential equality) is not invoked. However, Point3D.Equals invokes Point.Equals because Point implements Equals in a manner that provides value equality.

using System;
public class Point: object {
 int x, y;
 public override bool Equals(Object obj) {
 //Check for null and compare run-time types.
 if (obj == null || GetType() != obj.GetType()) return false;
 Point p = (Point)obj;
 return (x == p.x) && (y == p.y);
 }
 public override int GetHashCode() {
 return x ^ y;
 }
}

class Point3D: Point {
 int z;
 public override bool Equals(Object obj) {
 return base.Equals(obj) && z == ((Point3D)obj).z;
 }
 public override int GetHashCode() {
 return base.GetHashCode() ^ z;
 }
}

The Point.Equals method checks that the obj argument is non-null and that it references an instance of the same type as this object. If either of those checks fail, the method returns false. The System.Object.Equals(System.Object) method uses System.Object.GetType to determine whether the run-time types of the two objects are identical. (Note that typeof is not used here because it returns the static type.) If instead the method had used a check of the form

<doc:param name="obj"/>
is Point , the check would return true in cases where obj is an instance of a subclass of Point , even though obj and the current instance are not of the same runtime type. Having verified that both objects are of the same type, the method casts obj to type Point and returns the result of comparing the instance variables of the two objects.

In Point3D.Equals , the inherited Equals method is invoked before anything else is done; the inherited Equals method checks to see that obj is non-null, that obj is an instance of the same class as this object, and that the inherited instance variables match. Only when the inherited Equals returns true does the method compare the instance variables introduced in the subclass. Specifically, the cast to Point3D is not executed unless obj has been determined to be of type Point3D or a subclass of Point3D .

Example 3:

In the previous example, operator == (the equality operator) is used to compare the individual instance variables. In some cases, it is appropriate to use the System.Object.Equals(System.Object) method to compare instance variables in an Equals implementation, as shown in the following example:

using System;
class Rectangle {
 Point a, b;
 public override bool Equals(Object obj) {
 if (obj == null || GetType() != obj.GetType()) return false;
 Rectangle r = (Rectangle)obj;
 //Use Equals to compare instance variables
 return a.Equals(r.a) && b.Equals(r.b);
 }
 public override int GetHashCode() {
 return a.GetHashCode() ^ b.GetHashCode();
 }
}

Example 4:

In some languages, such as C#, operator overloading is supported. When a type overloads operator ==, it should also override the System.Object.Equals(System.Object) method to provide the same functionality. This is typically accomplished by writing the Equals method in terms of the overloaded operator ==. For example:

using System;
public struct Complex {
 double re, im;
 public override bool Equals(Object obj) {
 return obj is Complex && this == (Complex)obj;
 }
 public override int GetHashCode() {
 return re.GetHashCode() ^ im.GetHashCode();
 }
 public static bool operator ==(Complex x, Complex y) {
 return x.re == y.re && x.im == y.im;
 }
 public static bool operator !=(Complex x, Complex y) {
 return !(x == y);
 }
}

Because Complex is a C# struct (a value type), it is known that there will be no subclasses of Complex . Therefore, the System.Object.Equals(System.Object) method need not compare the GetType() results for each object, but can instead use the is operator to check the type of the obj parameter.

public static System.Boolean Equals(System.Object objA, System.Object objB)

Determines whether two object references are equal.

Parameter objA: First object to compare.

Parameter objB: Second object to compare.

Returns: true if one or more of the following statements is true: otherwise returns false.

This static method checks for null references before it calls objA.Equals(objB ) and returns false if either objA or objB is null. If the Equals(object obj) implementation throws an exception, this method throws an exception.

Example:

The following example demonstrates the System.Object.Equals(System.Object) method.

using System;

public class MyClass {
   public static void Main() {
   string s1 = "Tom";
   string s2 = "Carol";
   Console.WriteLine("Object.Equals(\"{0}\", \"{1}\") => {2}", 
      s1, s2, Object.Equals(s1, s2));

   s1 = "Tom";
   s2 = "Tom";
   Console.WriteLine("Object.Equals(\"{0}\", \"{1}\") => {2}", 
      s1, s2, Object.Equals(s1, s2));

   s1 = null;
   s2 = "Tom";
   Console.WriteLine("Object.Equals(null, \"{1}\") => {2}",
       s1, s2, Object.Equals(s1, s2));

   s1 = "Carol";
   s2 = null;
   Console.WriteLine("Object.Equals(\"{0}\", null) => {2}", 
       s1, s2, Object.Equals(s1, s2));

   s1 = null;
   s2 = null;
   Console.WriteLine("Object.Equals(null, null) => {2}", 
       s1, s2, Object.Equals(s1, s2));
   }
}

The output is

Object.Equals("Tom", "Carol") => False

Object.Equals("Tom", "Tom") => True

Object.Equals(null, "Tom") => False

Object.Equals("Carol", null) => False

Object.Equals(null, null) => True

public System.Void Finalize()

Allows a System.Object to perform cleanup operations before the memory allocated for the System.Object is automatically reclaimed.

During execution, System.Object.Finalize is automatically called after an object becomes inaccessible, unless the object has been exempted from finalization by a call to System.GC.SuppressFinalize(System.Object). During shutdown of an application domain, System.Object.Finalize is automatically called on objects that are not exempt from finalization, even those that are still accessible. System.Object.Finalize is automatically called only once on a given instance, unless the object is re-registered using a mechanism such as System.GC.ReRegisterForFinalize(System.Object) and System.GC.SuppressFinalize(System.Object) has not been subsequently called. Conforming implementations of the CLI are required to make every effort to ensure that for every object that has not been exempted from finalization, the System.Object.Finalize method is called after the object becomes inaccessible. However, there may be some circumstances under which Finalize is not called. Conforming CLI implementations are required to explicitly specify the conditions under which Finalize is not guaranteed to be called. For example, Finalize might not be guaranteed to be called in the event of equipment failure, power failure, or other catastrophic system failures. In addition to System.GC.ReRegisterForFinalize(System.Object) and System.GC.SuppressFinalize(System.Object), conforming implementations of the CLI are allowed to provide other mechanisms that affect the behavior of System.Object.Finalize . Any mechanisms provided are required to be specified by the CLI implementation. The order in which the Finalize methods of two objects are run is unspecified, even if one object refers to the other. The thread on which Finalize is run is unspecified. Every implementation of System.Object.Finalize in a derived type is required to call its base type's implementation of Finalize . This is the only case in which application code calls System.Object.Finalize . The System.Object.Finalize implementation does nothing. A type should implement Finalize when it uses unmanaged resources such as file handles or database connections that must be released when the managed object that uses them is reclaimed. Because Finalize methods may be invoked in any order (including from multiple threads), synchronization may be necessary if the Finalize method may interact with other objects, whether accessible or not. Furthermore, since the order in which Finalize is called is unspecified, implementers of Finalize (or of destructors implemented through overriding Finalize) must take care to correctly handle references to other objects, as their Finalize method may already have been invoked. In general, referenced objects should not be considered valid during finalization. See the System.IDisposable interface for an alternate means of disposing of resources. For C# developers: Destructors are the C# mechanism for performing cleanup operations. Destructors provide appropriate safeguards, such as automatically calling the base type's destructor. In C# code, System.Object.Finalize cannot be called or overridden.

public virtual System.Int32 GetHashCode()

Generates a hash code for the current instance.

Returns: A System.Int32 containing the hash code for the current instance.

System.Object.GetHashCode serves as a hash function for a specific type. A hash function is used to quickly generate a number (a hash code) corresponding to the value of an object. Hash functions are used with hashtables. A good hash function algorithm rarely generates hash codes that collide. For more information about hash functions, see The Art of Computer Programming , Vol. 3, by Donald E. Knuth. All implementations of System.Object.GetHashCode are required to ensure that for any two object references x and y, if x.Equals(y) == true, then x.GetHashCode() == y.GetHashCode(). Hash codes generated by System.Object.GetHashCode need not be unique. Implementations of System.Object.GetHashCode are not permitted to throw exceptions. The System.Object.GetHashCode implementation attempts to produce a unique hash code for every object, but the hash codes generated by this method are not guaranteed to be unique. Therefore, System.Object.GetHashCode may generate the same hash code for two different instances. It is recommended (but not required) that types overriding System.Object.GetHashCode also override System.Object.Equals(System.Object) . Hashtables cannot be relied on to work correctly if this recommendation is not followed. Use this method to obtain the hash code of an object. Hash codes should not be persisted (i.e. in a database or file) as they are allowed to change from run to run.

Example:

Example 1

In some cases, System.Object.GetHashCode is implemented to simply return an integer value. The following example illustrates an implementation of System.Int32.GetHashCode , which returns an integer value:

using System;
public struct Int32 {
 int value;
 //other methods...

 public override int GetHashCode() {
 return value;
 }
}

Example 2

Frequently, a type has multiple data members that can participate in generating the hash code. One way to generate a hash code is to combine these fields using an xor (exclusive or) operation, as shown in the following example:

using System;
public struct Point {
 int x;
 int y; 
 //other methods
 
 public override int GetHashCode() {
 return x ^ y;
 }
}

Example 3

The following example illustrates another case where the type's fields are combined using xor (exclusive or) to generate the hash code. Notice that in this example, the fields represent user-defined types, each of which implements System.Object.GetHashCode (and should implement System.Object.Equals(System.Object) as well):

using System;
public class SomeType {
 public override int GetHashCode() {
 return 0;
 }
}

public class AnotherType {
 public override int GetHashCode() {
 return 1;
 }
}

public class LastType {
 public override int GetHashCode() {
 return 2;
 }
}
public class MyClass {
 SomeType a = new SomeType();
 AnotherType b = new AnotherType();
 LastType c = new LastType();

 public override int GetHashCode () {
 return a.GetHashCode() ^ b.GetHashCode() ^ c.GetHashCode();
 }
}

Avoid implementing System.Object.GetHashCode in a manner that results in circular references. In other words, if AClass.GetHashCode calls BClass.GetHashCode, it should not be the case that BClass.GetHashCode calls AClass.GetHashCode.

Example 4

In some cases, the data member of the class in which you are implementing System.Object.GetHashCode is bigger than a System.Int32. In such cases, you could combine the high order bits of the value with the low order bits using an XOR operation, as shown in the following example:

using System;
public struct Int64 {
 long value;
 //other methods...

 public override int GetHashCode() {
 return ((int)value ^ (int)(value >> 32));
 }
}

public System.Type GetType()

Gets the type of the current instance.

Returns: The instance of System.Type that represents the run-time type (the exact type) of the current instance.

For two objects x and y that have identical run-time types, System.Object.ReferenceEquals(System.Object,System.Object)(x.GetType(),y.GetType()) returns true .

Example:

The following example demonstrates the fact that System.Object.GetType returns the run-time type of the current instance:

using System;
public class MyBaseClass: Object {
}
public class MyDerivedClass: MyBaseClass {
}
public class Test {
   public static void Main() {
   MyBaseClass myBase = new MyBaseClass();
   MyDerivedClass myDerived = new MyDerivedClass();

   object o = myDerived;
   MyBaseClass b = myDerived;

   Console.WriteLine("mybase: Type is {0}", myBase.GetType());
   Console.WriteLine("myDerived: Type is {0}", myDerived.GetType());
   Console.WriteLine("object o = myDerived: Type is {0}", o.GetType());
   Console.WriteLine("MyBaseClass b = myDerived: Type is {0}", b.GetType());
   }
}

The output is

mybase: Type is MyBaseClass

myDerived: Type is MyDerivedClass

object o = myDerived: Type is MyDerivedClass

MyBaseClass b = myDerived: Type is MyDerivedClass

protected System.Object MemberwiseClone()

Creates a shallow copy of the current instance.

Returns: A shallow copy of the current instance. The run-time type (the exact type) of the returned object is the same as the run-time type of the object that was copied.

System.Object.MemberwiseClone creates a new instance of the same type as the current instance and then copies each of the object's non-static fields in a manner that depends on whether the field is a value type or a reference type. If the field is a value type, a bit-by-bit copy of all the field's bits is performed. If the field is a reference type, only the reference is copied. The algorithm for performing a shallow copy is as follows (in pseudo-code): for each instance field f in this instance if (f is a value type) bitwise copy the field if (f is a reference type) copy the reference end for loop This mechanism is referred to as a shallow copy because it copies rather than clones the non-static fields. Because System.Object.MemberwiseClone implements the above algorithm, for any object, a, the following statements are required to be true: System.Object.MemberwiseClone does not call any of the type's constructors. If System.Object.Equals(System.Object) has been overridden, a.MemberwiseClone().Equals(a) might return false . For an alternate copying mechanism, see System.ICloneable . System.Object.MemberwiseClone is protected (rather than public) to ensure that from verifiable code it is only possible to clone objects of the same class as the one performing the operation (or one of its subclasses). Although cloning an object does not directly open security holes, it does allow an object to be created without running any of its constructors. Since these constructors may establish important invariants, objects created by cloning may not have these invariants established, and this may lead to incorrect program behavior. For example, a constructor might add the new object to a linked list of all objects of this class, and cloning the object would not add the new object to that list -- thus operations that relied on the list to locate all instances would fail to notice the cloned object. By making the method protected, only objects of the same class (or a subclass) can produce a clone and implementers of those classes are (presumably) aware of the appropriate invariants and can arrange for them to be true without necessarily calling a constructor.

Example:

The following example shows a class called MyClass as well as a representation of the instance of MyClass returned by System.Object.MemberwiseClone .

using System;
class MyBaseClass {
   public static string CompanyName = "My Company";
   public int age;
   public string name;
}

class MyDerivedClass: MyBaseClass {

   static void Main() {
   
   //Create an instance of MyDerivedClass
   //and assign values to its fields.
   MyDerivedClass m1 = new MyDerivedClass();
   m1.age = 42;
   m1.name = "Sam";

   //Do a shallow copy of m1
   //and assign it to m2.
   MyDerivedClass m2 = (MyDerivedClass) m1.MemberwiseClone();
   }
}

A graphical representation of m1 and m2 might look like this


+---------------+

|     42        |                           m1 

+---------------+

|     +---------|-----------------> "Sam" 

+---------------+                    /|\ 

                                      | 

+---------------+                     | 

|     42        |                     |      m2 

+---------------+                     | 

|      +--------|---------------------| 

+---------------+

public static System.Boolean ReferenceEquals(System.Object objA, System.Object objB)

Determines whether two object references are identical.

Parameter objA: First object to compare.

Parameter objB: Second object to compare.

Returns: True if a and b refer to the same object or are both null references; otherwise, false.

This static method provides a way to compare two objects for reference equality. It does not call any user-defined code, including overrides of System.Object.Equals(System.Object) .

Example:

using System;
class MyClass {
   static void Main() {
   object o = null;
   object p = null;
   object q = new Object();
   Console.WriteLine(Object.ReferenceEquals(o, p));
   p = q;
   Console.WriteLine(Object.ReferenceEquals(p, q));
   Console.WriteLine(Object.ReferenceEquals(o, p));
   }
}

The output is

True

True

False

public virtual System.String ToString()

Creates and returns a System.String representation of the current instance.

Returns: A System.String representation of the current instance.

System.Object.ToString returns a string whose content is intended to be understood by humans. Where the object contains culture-sensitive data, the string representation returned by System.Object.ToString takes into account the current system culture. For example, for an instance of the System.Double class whose value is zero, the implementation of System.Double.ToString might return "0.00" or "0,00" depending on the current UI culture. Although there are no exact requirements for the format of the returned string, it should as much as possible reflect the value of the object as perceived by the user. System.Object.ToString is equivalent to calling System.Object.GetType to obtain the System.Type object for the current instance and then returning the result of calling the System.Object.ToString implementation for that type. The value returned includes the full name of the type. It is recommended, but not required, that System.Object.ToString be overridden in a derived class to return values that are meaningful for that type. For example, the base data types, such as System.Int32, implement System.Object.ToString so that it returns the string form of the value the object represents. Subclasses that require more control over the formatting of strings than System.Object.ToString provides should implement System.IFormattable, whose System.Object.ToString method uses the culture of the current thread.

Example:

The following example outputs the textual description of the value of an object of type System.Object to the console.

using System;

class MyClass {
   static void Main() {
      object o = new object();
      Console.WriteLine (o.ToString());
   }
}

The output is

System.Object


Functions inherited from System.Security.IPermission:

public System.Security.IPermission Copy()

Returns a System.Security.IPermission object of the same type and containing the same values as the current instance.

Returns: A new System.Security.IPermission object of the same type and containing the same values as the current instance.

The object returned by this method is required to be a deep copy of the current instance; any objects referenced by the current instance are duplicated in the copy. Implement this method to provide the system with a means of duplicating permission objects. Use this method to obtain a copy of the current instance that is identical to the current instance.

public System.Void Demand()

Forces a System.Security.SecurityException if all callers do not have the permission specified by the current instance.

Throws: : A caller does not have the permission specified by the current instance.

The permission check for System.Security.IPermission.Demand begins with the immediate caller of the code that calls this method and continues until all callers have been checked or a caller has been found that is not granted the demanded permission, in which case a System.Security.SecurityException exception is thrown. Notifies the system that a security check is required for all callers of the method that invokes System.Security.IPermission.Demand. All callers are required to have the permissions described by the current instance. If one of the callers asserts the permissions and that caller has the permissions, the system is required to allow all callers that have not been checked to bypass the security check. If the security check fails, a System.Security.SecurityException is thrown by the system. Use this method to ensure that callers that call the method containing a System.Security.IPermission.Demand call have the permissions described by the current instance.

public System.Security.IPermission Intersect(System.Security.IPermission target)

Returns an object that is the intersection of the current instance and the specified System.Security.IPermission object.

Parameter target: An object of the same type as the current instance to intersect with the current instance.

Returns: A new System.Security.IPermission object that is the same type as the current instance and represents the intersection of the current instance and target. If the intersection is empty, or target is null, returns null. If the current instance is unrestricted, returns a copy of target. If target is unrestricted, returns a copy of the current instance.

Throws: : target is not null and is not of the same type as the current instance.

The object returns by System.Security.IPermission.Intersect(System.Security.IPermission) is a permission that secures the resources and operations secured by two System.Security.IPermission objects: a demand passes the intersection of two objects only if it passes both of the objects. If target is not null and is not of the same type as the current instance, a System.ArgumentException exception is required to be thrown. The following statements are required to be true for all implementations of the System.Security.IPermission.Intersect(System.Security.IPermission) method. X and Y represent non-null System.Security.IPermission object references. Use this method to obtain the set of permissions that are described both by the current instance and the specified object.

public System.Boolean IsSubsetOf(System.Security.IPermission target)

Determines whether the current instance is a subset of the specified object.

Parameter target: A System.Security.IPermission object of the same type as the current instance that is to be tested for the subset relationship.

Returns: true if the current instance is a subset of target ; otherwise, false. If the current instance is unrestricted, and target is not, returns false. If target is unrestricted, returns true. If target is null and the current instance does not secure any resources or operations, returns true. If target is null and the current instance secures one or more resources or operations, returns false .

Throws: : target is not null and is not of the same type as the current instance.

The current instance is a subset of target if the current instance specifies a set of accesses to resources or operations that is wholly contained by target. For example, a permission that represents read access to a file is a subset of a permission that represents read and write access to the file. If target is not null and is not of the same type as the current instance, a System.ArgumentException exception is required to be thrown. The following statements are required to be true for all implementations of the System.Security.IPermission.IsSubsetOf(System.Security.IPermission) method. X, Y, and Z represent non-null System.Security.IPermission objects. Use this method to determine if the permissions described by the current instance are also described by the specified object.

public System.Security.IPermission Union(System.Security.IPermission target)

Returns an object that is the union of the current instance and the specified object.

Parameter target: A System.Security.IPermission object of the same type as the current instance to combine with the current instance.

Returns: A new System.Security.IPermission object of the same type as the current instance that represents the union of the current instance and target.

Throws: : target is not null and is not of the same type as the current instance.

The object returned by System.Security.IPermission.Union(System.Security.IPermission) is a permission that represents the permissions described by the current instance and those described by target . Any demand that passes either the current instance or target is required to pass the union of the two. If target is not null and is not of the same type as the current instance, a System.ArgumentException exception is required to be thrown. The following statements are required to be true for all implementations of the System.Security.IPermission.Union(System.Security.IPermission) method. X and Y represent non-null System.Security.IPermission objects. Use this method to obtain a System.Security.IPermission object of the same type as the current instance and target that describes the permissions described by the current instance and those described by target.