Simple Classes

A Slice class definition is similar to a structure definition, but uses the class keyword. For example:

class TimeOfDay {
    short hour;         // 0 - 23
    short minute;       // 0 - 59
    short second;       // 0 - 59

Apart from the keyword class, this definition is identical to the structure example. You can use a Slice class wherever you can use a Slice structure (but, as we will see shortly, for performance reasons, you should not use a class where a structure is sufficient). Unlike structures, classes can be empty:

class EmptyClass {};    // OK
struct EmptyStruct {};  // Error

Much the same design considerations as for empty interfaces apply to empty classes: you should at least stop and rethink your approach before committing yourself to an empty class.

A class can define any number of data members, including optional data members. You can also specify a default value for a data member if its type is one of the following:

For example:

class Location {
    string name;
    Point pt;
    bool display = true;
    string source = "GPS";

The legal syntax for literal values is the same as for Slice constants, and you may also use a constant as a default value. The language mapping guarantees that data members are initialized to their declared default values using a language-specific mechanism.

See Also