The Larch/C++ keyword this can only be used in the
specification of a member function.
It has the same meaning as it does in C++
(see Section r.9.3.1 in [Stroustrup91]).
When used in a (non-const) member function of class T,
which is associated with sort ValT
(often valT is just T, but see section 2.7 Types and Sorts),
this has sort ConstObj[Ptr[Obj[ValT]]].
When used in a const member function,
the sort is ConstObj[Ptr[ConstObj[ValT]]].
For example, in the specification of a member function of
a class Person (see section 7.1.1 A First Class Design (Person)
for more details on this example),
the sort of this is ConstObj[Ptr[Obj[Person]]].
However, in the specification of a const member function
of class Person,
such as years_old,
the sort of this is
ConstObj[Ptr[ConstObj[Person]]].
The Larch/C++ keyword self is a shorthand for (*(this\any)),
which is dereferencing the pointer value found in this in some
visible state.
See section 6.2.1 State Functions for details about the state-function \any
(and see section 6.2 Mutation for the notion of state.)
(Any visible state is acceptable, because the this pointer itself
cannot be assigned to in a C++ program.)
Thus a form such as self^ is shorthand for (*(this\any))^.
The keyword self can only be used in the specification of a member
function.
When used in a member function of class T,
which is associated with sort ValT,
self has sort Obj[ValT].
Most often self is much more convenient for specification
than this.
For example, in the specification of a member function of
a class Person (see section 7.1.1 A First Class Design (Person)
for more details on this example),
the sort of self is Obj[Person].
However, in the specification of a const member function
of class Person,
such as years_old,
the sort of self is
ConstObj[Person].
See section 7 Class Specifications for more examples.
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