Classes

Every user-defined class is a subclass of a parent class (which may be java.lang.Object). A value of the parent class can be cast to the type of an object, an object can be concatenated to a string, its type can be queried, and references can be compared for equality.

An OIL class is used as a template to create the operations required by the Java class:

Reference types[9]:

CLASS classOps() BEGIN
  OPER
    strclsOp(classOps,stringType): stringType;
    clsstrOp(stringType,classOps): stringType;
    clseqOp, clsneOp(classOps,classOps): boolType;
    clsCondOp(classOps,classOps): classOps;

  COERCION
    (nullType): classOps;
END;

CLASS classInh(parentClass) BEGIN
  OPER
    narrowOp(parentClass): classInh;

  COERCION
    (classInh): parentClass;
END;

INDICATION
  plusInd:        strclsOp, clsstrOp;
  castInd:        narrowOp;
  conditionalInd: clsCondOp;
  eqlInd:         clseqOp;
  neqInd:         clsneOp;
  equalInd:       clsCondOp;

This macro is defined in definitions 9, 10, 11, and 12.
This macro is invoked in definition 4.

A special type is used as the type of a class literal, and we need a bogus operator to define it:

Reference types[10]:

OPER classOp(classType): classType;

This macro is defined in definitions 9, 10, 11, and 12.
This macro is invoked in definition 4.