6}

7}

8end example]

9The handling of attributes specified on the type or type parameters of different parts of a partial declaration

10is discussed in §24.2

1117.2 Class members

12The members of a class consist of the members introduced by its class-member-declarations and the

13members inherited from the direct base class.

14class-member-declarations:

29The members of a class are divided into the following categories:

30• Constants, which represent constant values associated with that class (§17.3).

31• Fields, which are the variables of that class (§17.4).

32• Methods, both non-generic and generic, which implement the computations and actions that can be

33performed by that class (§17.5, §26.6).

34• Properties, which define named characteristics and the actions associated with reading and writing those

35characteristics (§17.6).

36• Events, which define notifications that can be generated by that class (§17.7).

37• Indexers, which permit instances of that class to be indexed in the same way as arrays (§17.8).

38• Operators, which define the expression operators that can be applied to instances of that class (§17.9).

39• Instance constructors, which implement the actions required to initialize instances of that class (§17.10)

40• Destructors, which implement the actions to be performed before instances of that class are permanently

41discarded (§17.12).

42• Static constructors, which implement the actions required to initialize that class itself (§17.11).

43• Types, which represent the types that are local to that class (§16.6).

44Members that can contain executable code are collectively known as the function members of the class. The

45function members of a class are the methods, properties, events, indexers, operators, instance constructors,

46destructors, and static constructors of that class.

261

C# LANGUAGE SPECIFICATION

1A class-declaration creates a new declaration space (§10.3), and the type-parameters and the class-member-

2declarations immediately contained by the class-declaration introduce new members into this declaration

3space. The following rules apply to class-member-declarations:

4• Instance constructors, destructors, and static constructors shall have the same name as the immediately

5enclosing class. All other members shall have names that differ from the name of the immediately

6enclosing class.

7• The name of a type parameter in the type-parameter-list of a class declaration shall differ from the

8names of all other type parameters in the same type-parameter-list and shall differ from the name of the

9class and the names of all members of the class.

10• The name of a type must differ from the names of all non-type members declared in the same class. If

11two or more type declarations share the same fully qualified name, the declarations must have the partial

12modifier (§17.1.4) and these declarations combine to define a single type. [Note: Since the fully

13qualified name of a type declaration encodes the number of type parameters, two distinct types may

14share the same name as long as they have different number of type parameters. end note]

15• The name of a constant, field, property, or event shall differ from the names of all other members

16declared in the same class.

17• The name of a method shall differ from the names of all other non-methods declared in the same class.

18In addition, the signature (§10.6) of a method shall differ from the signatures of all other methods

19declared in the same class, and two methods declared in the same class shall not have signatures that

20differ solely by ref and out.

21• The signature of an instance constructor shall differ from the signatures of all other instance constructors

22declared in the same class, and two constructors declared in the same class shall not have signatures that

23differ solely by ref and out.

24• The signature of an indexer shall differ from the signatures of all other indexers declared in the same

25class.

26• The signature of an operator shall differ from the signatures of all other operators declared in the same

27class.

28The inherited members of a class (§17.2.1) are not part of the declaration space of a class. [Note: Thus, a

29derived class is allowed to declare a member with the same name or signature as an inherited member

30(which in effect hides the inherited member). end note]

31The set of members of a type declared in multiple parts (§17.1.4) is the union of the members declared in

32each part. The bodies of all parts of the type declaration share the same declaration space (§10.3), and the

33scope of each member (§10.7) extends to the bodies of all the parts. The accessibility domain of any member

34always includes all the parts of the enclosing type; a private member declared in one part is freely

35accessible from another part. It is a compile-time error to declare the same member in more than one part of

36the type, unless that member is a type having the partial modifier. [Example:

37partial class A

38{

43}

44}

45partial class A

46{

262

4}

5}

6end example]

7The ordering of members within a type declared in multiple parts is undefined. [Note: Although the ordering

8of members within a type is not significant to C# code, it may be significant when interfacing with other

9languages and environments. end note]

1017.2.1 Inheritance

11A class inherits the members of its direct base class. Inheritance means that a class implicitly contains all

12members of its direct base class, except for the instance constructors, destructors, and static constructors of

13the base class. Some important aspects of inheritance are:

14• Inheritance is transitive. If C is derived from B, and B is derived from A, then C inherits the members

15declared in A as well as the members declared in B.

16• A derived class extends its direct base class. A derived class can add new members to those it inherits,

17but it cannot remove the definition of an inherited member.

18• Instance constructors, destructors, and static constructors are not inherited, but all other members are,

19regardless of their declared accessibility (§10.5). However, depending on their declared accessibility,

20inherited members might not be accessible in a derived class.

21• A derived class can hide (§10.7.1.2) inherited members by declaring new members with the same name

22or signature. However, hiding an inherited member does not remove that member—it merely means that

23member will not be found by member lookup within the derived class.

24• An instance of a class contains a set of all instance fields declared in the class and its base classes, and

25an implicit conversion (§13.1.4) exists from a derived class type to any of its base class types. Thus, a

26reference to an instance of some derived class can be treated as a reference to an instance of any of its

27base classes.

28• A class can declare virtual methods, properties, indexers, and events, and derived classes can override

29the implementation of these function members. This enables classes to exhibit polymorphic behavior

30wherein the actions performed by a function member invocation varies depending on the run-time type

31of the instance through which that function member is invoked.

32• Members inherited from a constructed generic type are inherited after type substitution. That is, any

33constituent types in the member have the base class declaration’s type parameters replaced with the

34corresponding type arguments used in the class-base specification.

35[Example: In the example:

36class A<S>

37{

38public S field;

39}

40class B<T> : A<T[]>

41{

43public A<T> Meth(T t) { … }

44}

45class C : B<string>

46{

48// inherited: public A<string> Meth(string t);

49}

263