2 Criteria of object orientation n the previous chapter we explored the goals of the object-oriented method.As a preparation for parts B and C,in which we will discover the technical details of the method,it is useful to take a quick but wide glance at the key aspects of object-oriented development.Such is the aim of this chapter. One of the benefits will be to obtain a concise memento of what makes a system object-oriented.This expression has nowadays become so indiscriminately used that we need a list of precise properties under which we can assess any method,language or tool that its proponents claim to be O-O. This chapter limits its explanations to a bare minimum,so if this is your first reading you cannot expect to understand in detail all the criteria listed;explaining them is the task ofthe rest of the book.Consider this discussion a preview-not the real movie,just a trailer. Warning: Actually a warning is in order because unlike any good trailer this chapter is also SPOILER! what film buffs call a spoiler-it gives away some of the plot early.As such it breaks the step-by-step progression of this book,especially part B,which patiently builds the case for object technology by looking at issue after issue before deducing and justifying the solutions.If you like the idea of reading a broad overview before getting into more depth, this chapter is for you.But if you prefer not to spoil the pleasure of seeing the problems unfold and of discovering the solutions one by one,then you should simply skip it.You will not need to have read it to understand subsequent chapters. 2.1 ON THE CRITERIA Let us first examine the choice of criteria for assessing objectness. How dogmatic do we need to be? The list presented below includes all the facilities which I believe to be essential for the production of quality software using the object-oriented method.It is ambitious and may appear uncompromising or even dogmatic.What conclusion does this imply for an environment which satisfies some but not all of these conditions?Should one just reject such a half-hearted O-O environment as totally inadequate?2 Criteria of object orientation In the previous chapter we explored the goals of the object-oriented method. As a preparation for parts B and C, in which we will discover the technical details of the method, it is useful to take a quick but wide glance at the key aspects of object-oriented development. Such is the aim of this chapter. One of the benefits will be to obtain a concise memento of what makes a system object-oriented. This expression has nowadays become so indiscriminately used that we need a list of precise properties under which we can assess any method, language or tool that its proponents claim to be O-O. This chapter limits its explanations to a bare minimum, so if this is your first reading you cannot expect to understand in detail all the criteria listed; explaining them is the task of the rest of the book. Consider this discussion a preview — not the real movie, just a trailer. Actually a warning is in order because unlike any good trailer this chapter is also what film buffs call a spoiler — it gives away some of the plot early. As such it breaks the step-by-step progression of this book, especially part B, which patiently builds the case for object technology by looking at issue after issue before deducing and justifying the solutions. If you like the idea of reading a broad overview before getting into more depth, this chapter is for you. But if you prefer not to spoil the pleasure of seeing the problems unfold and of discovering the solutions one by one, then you should simply skip it. You will not need to have read it to understand subsequent chapters. 2.1 ON THE CRITERIA Let us first examine the choice of criteria for assessing objectness. How dogmatic do we need to be? The list presented below includes all the facilities which I believe to be essential for the production of quality software using the object-oriented method. It is ambitious and may appear uncompromising or even dogmatic. What conclusion does this imply for an environment which satisfies some but not all of these conditions? Should one just reject such a half-hearted O-O environment as totally inadequate? Warning: SPOILER!