Records

Record types are very similar to class types, except they are value types, instead of reference types.

Record declarations

There are several restrictions regarding records:

• All they inherit from the System.Value predefined class, though you cannot include an explicit inheritance clause in the record declaration.
• Records are considered as sealed types. You cannot create a new type by inheriting from a record.
• Since all record types are sealed, you cannot declare protected members in a record type.
• All record types have an implicitly declared parameterless constructor. You cannot explicitly declare a parameterless constructor for a record.
• Since you cannot define a parameterless constructor, you cannot associate initializers to instance field declarations.

Vector = record
public
    constructor(X, Y, Z: Double);

    property X, Y, Z: Double;

    method Equals(Other: Object): Boolean; override;
    method GetHashCode: Integer; override;

static public
    method= (V1, V2: Vector): Boolean;
    method<>(V1, V2: Vector): Boolean;

end;

Record implementations are identical to class implementations.

Overridable methods

If you need to compare instances from a record type, you should redefine the Equals method and the GetHashCode method. These methods are inherited from the System.Object class, but the inherited implementation for Equals, from System.Value type, is based on reflection, and it is not efficient at all.

Another consequence, if you redefine Equals and GetHashCode, is that you must redefine the equality and inequality operators.

See also

The Freya Programming Language
Type declarations
Nested types
Class declarations
Nullable types
Interface types
Delegate types
Type members