🏗️Software Engineering: Encapsulation (Just the Quotes)

"Object-oriented programming languages support encapsulation, thereby improving the ability of software to be reused, refined, tested, maintained, and extended. The full benefit of this support can only be realized if encapsulation is maximized during the design process. […] design practices which take a data-driven approach fail to maximize encapsulation because they focus too quickly on the implementation of objects." (Rebecca Wirfs-Brock, "Object-oriented Design: A. responsibility-driven approach", 1989)

"Object-oriented programming increases the value of these metrics by managing this complexity. The most effective tool available for dealing with complexity is abstraction. Many types of abstraction can be used, but encapsulation is the main form of abstraction by which complexity is managed in object-oriented programming. Programming in an object-oriented language, however, does not ensure that the complexity of an application will be well encapsulated. Applying good programming techniques can improve encapsulation, but the full benefit of object-oriented programming can be realized only if encapsulation is a recognized goal of the design process." (Rebecca Wirfs-Brock," Object-Oriented Design: A responsibility-driven approach", 1989)

"Programming in an object-oriented language, however, does not ensure that the complexity of an application will be well encapsulated. Applying good programming techniques can improve encapsulation, but the full benefit of object-oriented programming can be realized only if encapsulation is a recognized goal of the design process." (Rebecca Wirfs-Brock, "Object-oriented Design: A responsibility-driven approach", 1989)

"[...] encapsulation - also known as information hiding - prevents clients from seeing its inside view, were the behavior of the abstraction is implemented." (Grady Booch, "Object-Oriented Design With Applications", 1991)

"Encapsulation says that, not only are you allowed to take a simpler view of a complex concept, you are not allowed to look at any of the details of the complex concept. What you see is what you get - it's all you get!" (Steve C McConnell," Code Complete: A Practical Handbook of Software Construction", 1993)

"The concept of modularity is related to information hiding, encapsulation, and other design heuristics. But sometimes thinking about how to assemble a system from a set of black boxes provides insights that information hiding and encapsulation don't, so the concept is worth having in your back pocket." (Steve C McConnell," Code Complete: A Practical Handbook of Software Construction", 1993)

"Watch for coupling that's too tight. 'Coupling' refers to how tight the connection is between two classes. In general, the looser the connection, the better. Several general guidelines flow from this concept: Minimize accessibility of classes and members. Avoid friend classes, because they're tightly coupled. Make data private rather than protected in a base class to make derived classes less tightly coupled to the base class. Avoid exposing member data in a class's public interface. Be wary of semantic violations of encapsulation. Observe the 'Law of Demeter' [...]. Coupling goes hand in glove with abstraction and encapsulation. Tight coupling occurs when an abstraction is leaky, or when encapsulation is broken." (Steve C McConnell," Code Complete: A Practical Handbook of Software Construction", 1993)

"Encapsulation picks up where abstraction leaves off. Abstraction says, ‘You're allowed to look at an object at a high level of detail’. Encapsulation says, ‘Furthermore, you aren't allowed to look at an object at any other level of detail’." (Steve C McConnell, "Code Complete: A Practical Handbook of Software Construction" 2nd Ed., 2004)

"Making domain concepts explicit in your code means other programmers can gather the intent of the code much more easily than by trying to retrofit an algorithm into what they understand about a domain. It also means that when the domain model evolves - which it will, as your understanding of the domain grows - you are in a good position to evolve the code. Coupled with good encapsulation, the chances are good that the rule will exist in only one place, and that you can change it without any of the dependent code being any the wiser." (Dan North [in Kevlin Henney’s "97 Things Every Programmer Should Know", 2010]) 

"More generally, each unit of code, from a block to a library, should have a narrow interface. Less communication reduces the reasoning required. This means that getters that return internal state are a liability - don’t ask an object for information to work with. Instead, ask the object to do the work with the information it already has. In other words, encapsulation is all - and only - about narrow interfaces." (Yechiel Kimchi [in Kevlin Henney’s "97 Things Every Programmer Should Know", 2010])

"The primary intent behind the principle of encapsulation is to separate the interface and the implementation, which enables the two to change nearly independently. This separation of concerns allows the implementation details to be hidden from the clients who must depend only on the interface of the abstraction. If an abstraction exposes implementation details to the clients, it leads to undesirable coupling between the abstraction and its clients, which will impact the clients whenever the abstraction needs to change its implementation details. Providing more access than required can expose implementation details to the clients, thereby, violating the 'principle of hiding'." (Girish Suryanarayana et al, "Refactoring for Software Design Smells: Managing Technical Debt", 2015)

"The principle of encapsulation advocates separation of concerns and information hiding through techniques such as hiding implementation details of abstractions and hiding variations." (Girish Suryanarayana et al, "Refactoring for Software Design Smells: Managing Technical Debt", 2015)