21.1 Reading a Quick-Reference Entry

Each quick-reference entry contains quite a bit of information. The sections that follow describe the structure of a quick-reference entry, explaining what information is available, where it is found, and what it means. While reading the descriptions that follow, you will find it helpful to flip through the reference section itself to find examples of the described features.

21.1.1 Type Name, Namespace, Assembly, Type Category, and Flags

Each quick-reference entry begins with a four-part title that specifies the name, namespace (followed by the assembly in parentheses), and type category of the type, and may also specify various additional flags that describe the type. The type name appears in bold at the upper-left side of the title. The namespace and assembly appear in smaller print in the lower-left side, below the type name.

The upper-right portion of the title indicates the type category of the type (class, delegate, enum, interface, or struct). The "class" category may include modifiers such as sealed or abstract.

In the lower-right corner of the title, you may find a list of flags that describe the type. The possible flags and their meanings are as follows:

ECMA

Specifies that the type is part of the ECMA CLI specification.

serializable

Specifies that the type, or a base class, implements System.Runtime.Serialization.ISerializable or has been flagged with the System.Serializable attribute.

marshal by reference

This class, or a superclass, derives from System.MarshalByRefObject.

context bound

This class, or a superclass, derives from System.ContextBoundObject.

disposable

Specifies that the type implements the System.IDisposable interface.

flag

Specifies that the enumeration be marked with the System.FlagsAttribute attribute.

21.1.2 Description

The title of each quick-reference entry is followed by a short description of the most important features of the type. This description may be anywhere from a couple of sentences to several paragraphs long.

21.1.3 Synopsis

The most important part of every quick-reference entry is the synopsis, which follows the title and description. The synopsis for a type looks much like its source code, except that the member bodies are omitted and some additional annotations are added. If you know C# syntax, you know how to read the type synopsis.

The first line of the synopsis contains information about the type itself. It begins with a list of type modifiers, such as abstract and sealed. These modifiers are followed by the class, delegate, enum, interface, or struct keyword and then by the name of the type. The type name may be followed by a colon (:) and a base class or interfaces that the type implements.

The type definition line is followed by a list of the members that the type defines. This list includes only members that are explicitly declared in the type, are overridden from a base class, or are implementations of an interface member. Members that are simply inherited from a base class are not shown; you will need to look up the base class definition to find those members.

Once again, if you understand basic C# syntax, you should have no trouble making sense of these lines. The listing for each member includes the modifiers, type, and name of the member. For methods, the synopsis also includes the type and name of each method parameter. The member names are in boldface, so it is easy to scan the list of members looking for the one you want. The names of method parameters are in italics to indicate that they should not be used literally. The member listings are printed on alternating gray and white backgrounds to keep them visually separate.

21.1.3.1 Member availability and flags

Each member listing is a single line that defines the syntax for that member. These listings use C# syntax, so their meaning is immediately clear to any C# programmer. Some auxiliary information associated with each member synopsis, however, requires explanation.

The area to the right of the member synopsis displays a variety of flags that provide additional information about the member. Some flags indicate additional specification details that do not appear in the member syntax itself.

The following flags may be displayed to the right of a member synopsis:

overrides

Indicates that a method overrides a method in one of its base classes. The flag is followed by the name of the base class that the method overrides.

implements

Indicates that a method implements a method in an interface. The flag is followed by the name of the implemented interface.

=

For enumeration fields and constant fields, this flag is followed by the constant value of the field. Only constants of primitive and String types and constants with the value null are displayed. Some constant values are specification details, while others are implementation details. Some constants, such as System.BitConverter.IsLittleEndian, are platform dependent. Platform-dependent values shown in this book conform to the System.PlatformID.Win32NT platform (32-bit Windows NT, 2000, or XP). The reason why symbolic constants are defined, however, is so you can write code that does not rely directly upon the constant value. Use this flag to help you understand the type, but do not rely upon the constant values in your own programs.

21.1.3.2 Functional grouping of members

Within a type synopsis, the members are not listed in strict alphabetical order. Instead, they are broken down into functional groups and listed alphabetically within each group. Constructors, events, fields, methods, and properties are all listed separately. Instance methods are kept separate from shared (class) methods. Public members are listed separately from protected members. Grouping members by category breaks a type down into smaller, more comprehensible segments, making the type easier to understand. This grouping also makes it easier for you to find a desired member.

Functional groups are separated from one another in a type synopsis with comments, such as:

Public Constructors

or:

// Protected Instance Properties

or:

// Events

The various functional categories follow below (in the order in which they appear in a type synopsis):

Constructors

Displays the constructors for the type. Public and protected constructors are displayed separately in subgroupings. If a type defines no constructor at all, the compiler adds a default parameterless constructor that is displayed here. If a type defines only private constructors, it cannot be instantiated, so no constructor appears. Constructors are listed first because the first thing you do with most types is instantiate them by calling a constructor.

Fields

Displays all fields defined by the type, including constants. Public and protected fields are displayed in separate subgroups. Fields are listed here, near the top of the synopsis, because constant values are often used throughout the type as legal values for method parameters and return values.

Properties

Lists all the properties of the type, breaking them down into subgroups for public and protected shared properties and public and protected instance properties. After the property name, its accessors (get or set) are shown.

Static methods

Lists the static methods (class methods) of the type, broken down into subgroups for public shared methods and protected shared methods.

Public instance methods

Contains all public instance methods.

Protected instance methods

Contains all protected instance methods.

21.1.4 Class Hierarchy

For any type that has a nontrivial inheritance hierarchy, the synopsis is followed by a "Hierarchy" section. This section lists all of the base classes of the type, as well as any interfaces implemented by those base classes. It also lists any interfaces implemented by an interface. In the hierarchy listing, arrows indicate base class to derived class relationships, while the interfaces implemented by a type follow the type name in parentheses. For example, the following hierarchy indicates that System.IO.Stream implements IDisposable and extends MarshalByRefObject, which itself extends Object:

System.Object  System.MarshalByRefObject  System.IO.Stream(System.IDisposable)

If a type has subtypes, the "Hierarchy" section is followed by a "Subtypes" section that lists those subtypes. If an interface has implementations, the "Hierarchy" section is followed by an "Implementations" section that lists those implementations. While the "Hierarchy" section shows ancestors of the type, the "Subtypes" or "Implementations" section shows descendants.

21.1.5 Cross References

The hierarchy section of a quick-reference entry is followed by optional cross-reference sections that indicate other related types and methods that may be of interest. These sections include:

Passed to

This section lists all members (from other types) that are passed an object of this type as an argument, including properties whose values can be set to this type. It is useful when you have an object of a given type and want to know where it can be used.

Returned by

This section lists all members that return an object of this type, including properties whose values can take on this type. It is useful when you know that you want to work with an object of this type, but don't know how to obtain one.

Valid on

For attributes, this section lists the attribute targets that the attribute can be applied to.

Associated events

For delegates, this section lists the events it can handle.

21.1.6 A Note About Type Names

Throughout the quick reference, you'll notice that types are sometimes referred to by type name alone, and at other times are referred to by type name and namespace. If namespaces were always used, the type synopses would become long and hard to read. On the other hand, if namespaces were never used, it would sometimes be difficult to know what type was being referred to. The rules for including or omitting the namespace name are complex. However, they can be summarized as follows:

• If the type name alone is ambiguous, the namespace name is always used.

• If the type is part of the System namespace or is a commonly used type like System.Collection.ICollection, the namespace is omitted.

• If the type being referred to is part of the current namespace (and has a quick-reference entry in the current chapter), the namespace is omitted. The namespace is also omitted if the type being referred to is part of a namespace that contains the current namespace.