Simple Classes

2 min read

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

Slice

module M
{
    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, except in a dictionary key type or in the type of an optional field, optional parameter, or optional return value. Marshaling and unmarshaling a class instance costs more time and space than a structure.

Unlike structures, classes can be empty:

Slice

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

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

An integral type (byte, short, int, long)
A floating point type (float or double)
string
bool
enum

For example:

Slice

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 fields are initialized to their declared default values using a language-specific mechanism.

See Also