A.1. Reliance Operators

?-calculus also swept aside everything but the four required and necessary entities—objects, method, fields, and types—opening the way for simple analyses that are truly comprehensive. For example, given only four items to work with, there are only sixteen ways they can be combined. This point was illustrated in Table 2.2, which is reproduced here in Table A.1.

Table A.1. All interactions between entities of object-oriented programming

This table is small enough that we can pick it apart piece by piece. We can address most of this table at one shot by investigating Defines. An object defines a method inside of it, or a field, or perhaps a type. Objects such as namespaces or package objects can also define other objects within them. Methods can, in some languages, define inner methods and types within them but can almost always define objects and fields. Fields, by their nature, do not readily wrap or define other elements, but the type of the field, such as a class, can define any of the four elements.