2.2.4 Records

A record is a sequence of named variables, called the fields of the record. Different fields can have different types. The name and type of each field is statically determined by the record's type. The expression r.f designates the field named f in the record r.

A record type declaration has the form:

    TYPE T = RECORD FieldList END

where FieldList is a list of field declarations, each of which has the form:

    fieldName: Type := default

where fieldName is an identifier, Type is any non-empty type other than an open array type, and default is a constant expression. The field names must be distinct. A record is a member of T if it has fields with the given names and types, in the given order, and no other fields. Empty records are allowed.

The constant default is a default value used when a record is constructed or allocated. Either ``:= default'' or ``: Type'' can be omitted, but not both. If Type is omitted, it is taken to be the type of default. If both are present, the value of default must be a member of Type.

When a series of fields shares the same type and default, any fieldName can be a list of identifiers separated by commas. Such a list is shorthand for a list in which the type and default are repeated for each identifier. That is:

    f_1, ..., f_m: Type := default

is shorthand for:

    f_1: Type := default; ...; f_m: Type := default

This shorthand is eliminated from the expanded definition of the type. The default values are included.

Examples of record types:

    TYPE
      Time = RECORD
        seconds: INTEGER;
        milliseconds: [0..999]
      END;

      Alignment = {Left, Center, Right};

      TextWindowStyle = RECORD
         align          := Alignment.Center;
         font           := Font.Default;
         foreground     := Color.Black;
         background     := Color.White;
         margin, border := 2
      END