"The engineer must be able not only to design, but to execute. A draftsman may be able to design, but unless he is able to execute his designs to successful operation he cannot be classed as an engineer. The production engineer must be able to execute his work as he has planned it. This requires two qualifications in addition to technical engineering ability: He must know men, and he must have creative ability in applying good statistical, accounting, and 'system' methods to any particular production work he may undertake." (Hugo Diemer, "Industrial Engineering", 1905)
"A design may be called organic when there is an harmonious organization of the parts within the whole, according to structure, material, and purpose." (Eliot Noyes, "Organic Design in Home Furnishing", 1941)
"An engineering science aims to organize the design principles used in engineering practice into a discipline and thus to exhibit the similarities between different areas of engineering practice and to emphasize the power of fundamental concepts. In short, an engineering science is predominated by theoretical analysis and very often uses the tool of advanced mathematics." (Qian Xuesen, "Engineering Cybernetics", 1954)
"Design problems - generating or discovering alternatives - are complex largely because they involve two spaces, an action space and a state space, that generally have completely different structures. To find a design requires mapping the former of these on the latter. For many, if not most, design problems in the real world systematic algorithms are not known that guarantee solutions with reasonable amounts of computing effort. Design uses a wide range of heuristic devices - like means-end analysis, satisficing, and the other procedures that have been outlined - that have been found by experience to enhance the efficiency of search. Much remains to be learned about the nature and effectiveness of these devices." (Herbert A Simon, "The Logic of Heuristic Decision Making", [in "The Logic of Decision and Action"], 1966)
"But active programming consists of the design of new programs, rather than contemplation of old programs." (Niklaus Wirth, "Program Development by Stepwise Refinement", 1971)
"Clearly, programming courses should teach methods of design and construction, and the selected examples should be such that a gradual development can be nicely demonstrated." (Niklaus Wirth, "Program Development by Stepwise Refinement", 1971)
"A clean design is more easily modified as requirements change or as more is learned about what parts of the code consume significant amounts of execution time. A 'clever' design that fails to work or to run fast enough can often be salvaged only at great cost. Efficiency does not have to be sacrificed in the interest of writing readable code - rather, writing readable code is often the only way to ensure efficient programs that are also easy to maintain and modify." (Brian W Kernighan & Phillip J Plauger, "The Elements of Programming Style", 1974)
"Conceptual integrity is the most important consideration in system design." (Frederick P Brooks, "The Mythical Man-Month" , 1975)
"The hardest single part of building a software system is deciding precisely what to build." (Frederick P. Brooks, "The Mythical Man-Month", 1975)
"From the point of view of modern science, design is nothing, but from the point of view of engineering, design is everything. It represents the purposive adaptation of means to reach a preconceived end, the very essence of engineering." (Edwin T Layton Jr., "American Ideologies of Science and Engineering", Technology and Culture No. 4, 1976)
"Systems with unknown behavioral properties require the implementation of iterations which are intrinsic to the design process but which are normally hidden from view. Certainly when a solution to a well-understood problem is synthesized, weak designs are mentally rejected by a competent designer in a matter of moments. On larger or more complicated efforts, alternative designs must be explicitly and iteratively implemented. The designers perhaps out of vanity, often are at pains to hide the many versions which were abandoned and if absolute failure occurs, of course one hears nothing. Thus the topic of design iteration is rarely discussed. Perhaps we should not be surprised to see this phenomenon with software, for it is a rare author indeed who publicizes the amount of editing or the number of drafts he took to produce a manuscript." (Fernando J Corbató, "A Managerial View of the Multics System Development", 1977)
"We try to solve the problem by rushing through the design process so that enough time is left at the end of the project to uncover the errors that were made because we rushed through the design process." (Glenford Myers, "Composite/structured design", 1978)
"A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible. There are no prima donnas in engineering." (Freeman Dyson, "Disturbing the Universe", 1979)
"Overemphasis of efficiency leads to an unfortunate circularity in design: for reasons of efficiency early programming languages reflected the characteristics of the early computers, and each generation of computers reflects the needs of the programming languages of the preceding generation." (Kenneth E Iverson, "Notation as a Tool of Thought", 1979)
"Meta-design is much more difficult than design; it's easier to draw something than to explain how to draw it." (Donald E Knuth, "The METAFONTbook", 1986)
"The complexity of software is an essential property, not an accidental one. Hence, descriptions of a software entity that abstract away its complexity often abstracts away its essence." (Frederick P Brooks, "No Silver Bullet" , 1987)
"There are two ways of constructing a software design. One way is to make it so simple that there are obviously no deficiencies. And the other way is to make it so complicated that there are no obvious deficiencies." (Charles A R Hoare, [lecture] 1987)
"A design remedy that prevents bugs is always preferable to a test method that discovers them." (Boris Beizer, "Software Testing Techniques", 1990)
"Engineering knowledge reflects the fact that design does not take place for its own sake and in isolation." (Walter G Vincenti, "What Engineers Know and How They Know It", 1990)
"First law: The pesticide paradox. Every method you use to prevent or find bugs leaves a residue of subtler bugs against which those methods are ineffective." (Boris Beizer, "Software Testing Techniques", 1990)
"Extra features were once considered desirable. We now recognize that 'free' features are rarely free. Any increase in generality that does not contribute to reliability, modularity, maintainability, and robustness should be suspected." (Boris Beizer, "Software Testing Techniques", 1990)
"More than the act of testing, the act of designing tests is one of the best bug preventers known. The thinking that must be done to create a useful test can discover and eliminate bugs before they are coded - indeed, test-design thinking can discover and eliminate bugs at every stage in the creation of software, from conception to specification, to design, coding and the rest." (Boris Beizer, "Software Testing Techniques", 1990)
"Second law: The complexity barrier. Software complexity (and therefore that of bugs) grows to the limits of our ability to manage that complexity." (Boris Beizer, "Software Testing Techniques", 1990)
"If solutions could be offered within the existing system, there would be no need to design. Thus designers have to transcend the existing system. Their task is to create a different system or devise a new one. That is why designers say they can truly define the problem only in light of the solution. The solution informs them as to what the real problem is." (Béla H Bánáthy, "Systems Design of Education", 1991)
"No matter how vigorously a 'science' of design may be pushed, the successful design of real things in a contingent world will always be based more on art than on science. Unquantifiable judgments and choices are the elements that determine the way a design comes together. Engineering design is simply that kind of process. It always has been; it always will be. (Eugene S Ferguson , "Engineering and the Mind’s Eye", 1992)
"Design patterns are not about designs such as linked lists and hash tables that can be encoded in classes and reused as is. Nor are they complex, domain-specific designs for an entire application or subsystem. The design patterns [...] are descriptions of communicating objects and classes that are customized to solve a general design problem in a particular context." (Erich Gamma et al, "Design Patterns: Elements of Reusable Object-Oriented Software", 1994)
"Design patterns make it easier to reuse successful designs and architectures. Expressing proven techniques as design patterns makes them more accessible to developers of new systems. Design patterns help you choose design alternatives that make a system reusable and avoid alternatives that compromise reusability. Design patterns can even improve the documentation and maintenance of existing systems by furnishing an explicit specification of class and object interactions and their underlying intent. Put simply, design patterns help a designer get a design 'right' faster." (Erich Gamma et al, "Design Patterns: Elements of Reusable Object-Oriented Software", 1994)
"If a project has not achieved a system architecture, including its rationale, the project should not proceed to full-scale system development. Specifying the architecture as a deliverable enables its use throughout the development and maintenance process." (Barry Boehm, 1995)
"The methods of science include controlled experiments, classification, pattern recognition, analysis, and deduction. In the humanities we apply analogy, metaphor, criticism, and (e)valuation. In design we devise alternatives, form patterns, synthesize, use conjecture, and model solutions." (Béla H Bánáthy, "Designing Social Systems in a Changing World", 1996)
"Good design protects you from the need for too many highly accurate components in the system. But such design principles are still, to this date, ill-understood and need to be researched extensively. Not that good designers do not understand this intuitively, merely it is not easily incorporated into the design methods you were taught in school. Good minds are still needed in spite of all the computing tools we have developed." (Richard Hamming, "The Art of Doing Science and Engineering: Learning to Learn", 1997)
"The nature of our language tends to force us into 'yes-no', something is or is not, you either have a proof or you do not. But once we admit there is a changing standard of rigor we have to accept some proofs are more convincing than other proofs. If you view proofs on a scale much like probability, running from 0 to 1, then all proofs lie in the range and very likely never reach the upper limit of 1, certainty." (Richard Hamming, "The Art of Doing Science and Engineering: Learning to Learn", 1997)
"The woes of software engineering are not due to lack of tools or proper management, but largely due to lack of sufficient technical competence. A good designer must rely on experience; on precise, logical thinking; and on pedantic exactness. No magic will do. In light of all this, it is particularly sad that, in many informatics curricula, programming in the large is badly neglected. Design has become a non-topic." (Niklaus Wirth, [interview in Software Development] 1997)
"It’s really hard to design products by focus groups. A lot of times, people don’t know what they want until you show it to them." (Steve Jobs, BusinessWeek, 1998)
"Good design is also an act of communication between the designer and the user, except that all the communication has to come about by the appearance of the device itself. The device must explain itself." (Donald Norman, "The Design of Everyday Things", 2002)
"Domain-driven design is both a way of thinking and a set of priorities, aimed at accelerating software projects that have to deal with complicated domains." (Eric Evans, "Domain-Driven Design: Tackling complexity in the heart of software", 2003)
"If the architecture isolates the domain-related code in a way that allows a cohesive domain design loosely coupled to the rest of the system, then that architecture can probably support domain-driven DESIGN." (Eric Evans, "Domain-Driven Design: Tackling complexity in the heart of software", 2003)
"If the design, or some central part of it, does not map to the domain model, that model is of little value, and the correctness of the software is suspect. At the same time, complex mappings between models and design functions are difficult to understand and, in practice, impossible to maintain as the design changes. A deadly divide opens between analysis and design so that insight gained in each of those activities does not feed into the other." (Eric Evans, "Domain-Driven Design: Tackling complexity in the heart of software", 2003)
"Many things can put a project off course: bureaucracy, unclear objectives, and lack of resources, to name a few. But it is the approach to design that largely determines how complex software can become. When complexity gets out of hand, developers can no longer understand the software well enough to change or extend it easily and safely. On the other hand, a good design can create opportunities to exploit those complex features." (Eric Evans, "Domain-Driven Design: Tackling complexity in the heart of software", 2003)
"Models come in many varieties and serve many roles, even those restricted to the context of a software development project. Domain-driven design calls for a model that doesn’t just aid early analysis but is the very foundation of the design […] Tightly relating the code to an underlying model gives the code meaning and makes the model relevant." (Eric Evans, "Domain-Driven Design: Tackling complexity in the heart of software", 2003)
"Software design is a constant battle with complexity." (Eric Evans, "Domain-Driven Design: Tackling complexity in the heart of software", 2003)
"The aim of architectural design is to prepare overall specifications, derived from the needs and desires of the user, for subsequent design and construction stages. The first task for the architect in each design project is thus to determine what the real needs and desires of the user are […]" (George J Klir & Doug Elias, "Architecture of Systems Problem Solving" 2nd Ed, 2003)
"The effectiveness of an overall design is very sensitive to the quality and consistency of fine-grained design and implementation decisions. With a MODEL-DRIVEN DESIGN, a portion of the code is an expression of the model; changing that code changes the model. Programmers are modelers, whether anyone likes it or not. So it is better to set up the project so that the programmers do good modeling work." (Eric Evans, "Domain-Driven Design: Tackling complexity in the heart of software", 2003)
"Design is heuristic. Dogmatic adherence to any single methodology hurts creativity and hurts your programs." (Steve C McConnell, "Code Complete: A Practical Handbook of Software Construction" 2nd Ed., 2004)
"Design patterns provide the cores of ready-made solutions that can be used to solve many of software’s most common problems. Some software problems require solutions that are derived from first principles. But most problems are similar to past problems, and those can be solved using similar solutions, or patterns." (Steve C McConnell, "Code Complete: A Practical Handbook of Software Construction" 2nd Ed., 2004)
"In addition to their complexity-management benefit, design patterns can accelerate design discussions by allowing designers to think and discuss at a larger level of granularity." (Steve C McConnell, "Code Complete: A Practical Handbook of Software Construction" 2nd Ed., 2004)
"On small, informal projects, a lot of design is done while the programmer sits at the keyboard. 'Design' might be just writing a class interface in pseudocode before writing the details. It might be drawing diagrams of a few class relationships before coding them. It might be asking another programmer which design pattern seems like a better choice. Regardless of how it’s done, small projects benefit from careful design just as larger projects do, and recognizing design as an explicit activity maximizes the benefit you will receive from it." (Steve C McConnell, "Code Complete: A Practical Handbook of Software Construction" 2nd Ed., 2004)
"The flip side of the coin was that even good programmers and language designers tended to do terrible extensions when they were in the heat of programming, because design is something that is best done slowly and carefully." (Alan Kay, [ACM Queue A Conversation with Alan Kay Vol. 2 (9)] 2004-2005)
"A commitment to simplicity of design means addressing the essence of design - the abstractions on which software is built - explicitly and up front. Abstractions are articulated, explained, reviewed and examined deeply, in isolation from the details of the implementation. This doesn’t imply a waterfall process, in which all design and specification precedes all coding. But developers who have experienced the benefits of this separation of concerns are reluctant to rush to code, because they know that an hour spent on designing abstractions can save days of refactoring." (Daniel Jackson, "Software Abstractions", 2006)
"Abstractions matter to users too. Novice users want programs whose abstractions are simple and easy to understand; experts want abstractions that are robust and general enough to be combined in new ways. When good abstractions are missing from the design, or erode as the system evolves, the resulting program grows barnacles of complexity. The user is then forced to master a mass of spurious details, to develop workarounds, and to accept frequent, inexplicable failures." (Daniel Jackson, "Software Abstractions", 2006)
"Software is built on abstractions. Pick the right ones, and programming will flow naturally from design; modules will have small and simple interfaces; and new functionality will more likely fit in without extensive reorganization […] Pick the wrong ones, and programming will be a series of nasty surprises: interfaces will become baroque and clumsy as they are forced to accommodate unanticipated interactions, and even the simplest of changes will be hard to make." (Daniel Jackson, "Software Abstractions", 2006)
"Duplication is the primary enemy of a well-designed system. It represents additional work, additional risk, and additional unnecessary complexity." (Robert C Martin, "Clean Code: A Handbook of Agile Software Craftsmanship", 2008)
"Good software designs accommodate change without huge investments and rework. When we use code that is out of our control, special care must be taken to protect our investment and make sure future change is not too costly." (Robert C Martin, "Clean Code: A Handbook of Agile Software Craftsmanship", 2008)
"Whether you are designing systems or individual modules, never forget to use the simplest thing that can possibly work." (Robert C Martin, "Clean Code: A Handbook of Agile Software Craftsmanship", 2008)
"We see a lot of feature-driven product design in which the cost of features is not properly accounted. Features can have a negative value to customers because they make the products more difficult to understand and use. We are finding that people like products that just work. It turns out that designs that just work are much harder to produce that designs that assemble long lists of features." (Douglas Crockford, "JavaScript: The Good Parts", 2008)
"A good system design is based on a sound conceptual model (architecture). A system design that has no conceptual structure and little logic to its organization is ultimately going to be unsuccessful. Good architecture will address all the requirements of the system at the right level of abstraction." (Vasudeva Varma, "Software Architecture: A Case Based Approach", 2009)
"A systems approach is one that focuses on the system as a whole, specifically linking value judgments (what is desired) and design decisions (what is feasible). A true systems approach means that the design process includes the 'problem' as well as the solution. The architect seeks a joint problem–solution pair and understands that the problem statement is not fixed when the architectural process starts. At the most fundamental level, systems are collections of different things that together produce results unachievable by the elements alone." (Mark W Maier, "The Art Systems of Architecting" 3rd Ed., 2009)
"Design has the power to enrich our lives by engaging our emotions through image, form, texture, color, sound, and smell. The intrinsically human-centered nature of design thinking points to the next step: we can use our empathy and understanding of people to design experiences that create opportunities for active engagement and participation." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)
"Design is the bridging activity between gathering and implementation of software requirements that satisfies the required needs. […] The fundamental goal of design is to reduce the number of dependencies between modules, thus reducing the complexity of the system. This is also known as coupling; lesser the coupling the better is the design. On the other hand, higher the binding between elements within a module (known as cohesion) the better is the design." (Vasudeva Varma, "Software Architecture: A Case Based Approach", 2009)
"Design thinking taps into capacities we all have but that are overlooked by more conventional problem-solving practices. It is not only human-centered; it is deeply human in and of itself. Design thinking relies on our ability to be intuitive, to recognize patterns, to construct ideas that have emotional meaning as well as functionality, to express ourselves in media other than words or symbols." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)
"Modeling is the creation of abstractions or representations of the system to predict and analyze performance, costs, schedules, and risks and to provide guidelines for systems research, development, design, manufacture, and management. Modeling is the centerpiece of systems architecting - a mechanism of communication to clients and builders, of design management with engineers and designers, of maintaining system integrity with project management, and of learning for the architect, personally." (Mark W Maier, "The Art Systems of Architecting" 3rd Ed., 2009)
"Mostly we rely on stories to put our ideas into context and give them meaning. It should be no surprise, then, that the human capacity for storytelling plays an important role in the intrinsically human-centered approach to problem solving, design thinking." (Tim Brown, "Change by Design: How Design Thinking Transforms Organizations and Inspires Innovation", 2009)
"Taking a systems approach means paying close attention to results, the reasons we build a system. Architecture must be grounded in the client’s/user’s/customer’s purpose. Architecture is not just about the structure of components. One of the essential distinguishing features of architectural design versus other sorts of engineering design is the degree to which architectural design embraces results from the perspective of the client/user/customer. The architect does not assume some particular problem formulation, as “requirements” is fixed. The architect engages in joint exploration, ideally directly with the client/user/customer, of what system attributes will yield results worth paying for." (Mark W Maier, "The Art Systems of Architecting" 3rd Ed., 2009)
"A software design can be described as a collection of design decisions. These design decisions include decisions about what classes should be included, how classes should behave, and how they should interact with each other. Each and every design decision is influenced by previously made design decisions, constraints on the design, and the requirements. In turn, every design decision also impacts the design; it can narrow down the set of future design decisions considerably or widen the scope of possible design decisions. In other words, each and every design decision impacts and even changes the context of the design." (Girish Suryanarayana et al, "Refactoring for Software Design Smells: Managing Technical Debt", 2015)
"Design is the process of taking something that appears in the mind’s eye, modeling it in one or more of a number of ways, predicting how that thing will behave if it is made, and then making it, sometimes modifying the design as we make it. Design is what engineering is about. Furthermore, modeling is how engineering design is done. This includes mental models, mathematical models, computer models, plans and drawings, written language, and (sometimes) physical models." (William M Bulleit, "The Engineering Way of Thinking: The Idea", Structure [magazine], 2015)
"Development is a design process. Design processes are generally evaluated by the value they deliver rather than a conformance to plan. Therefore, it makes sense to move away from plan-driven projects and toward value-driven projects. […] The realization that the source code is part of the design, not the product, fundamentally rewires our understanding of software." (Sriram Narayan, "Agile IT Organization Design: For Digital Transformation and Continuous Delivery", 2015)
"How does a smell manifest in design? A smell occurs as a result of a combination of one or more design decisions. In other words, the design ecosystem itself is responsible for the creation of the smell. The presence of the smell in turn impacts the ecosystem in several ways. First, it is likely that the presence of the smell triggers new design decisions that are needed to address the smell! Second, the smell can potentially influence or constrain future design decisions as a result of which one or more new smells may manifest in the ecosystem. Third, smells also tend to have an effect on other smells. For instance, some smells amplify the effects of other smells, or co-occur with or act as precursors to other smells. Clearly, smells share a rich relationship with the ecosystem in which they occur." (Girish Suryanarayana et al, "Refactoring for Software Design Smells: Managing Technical Debt", 2015)
"Technical debt is the debt that accrues when you knowingly or unknowingly make wrong or non-optimal design decisions. [...] when a software developer opts for a quick fix rather than a proper well-designed solution, he introduces technical debt. It is okay if the developer pays back the debt on time. However, if the developer chooses not to pay or forgets about the debt created, the accrued interest on the technical debt piles up, just like financial debt, increasing the overall technical debt. The debt keeps increasing over time with each change to the software; thus, the later the developer pays off the debt, the more expensive it is to pay off. If the debt is not paid at all, then eventually the pile-up becomes so huge that it becomes immensely difficult to change the software. In extreme cases, the accumulated technical debt is so huge that it cannot be paid off anymore and the product has to be abandoned. Such a situation is called technical bankruptcy." (Girish Suryanarayana et al, "Refactoring for Software Design Smells: Managing Technical Debt", 2015)
"Designers need to be part engineer. Good design only exists in concert with engineering. That is because form has to follow function, so you focus on function and then give the object a shape to make it appealing." (Ferdinand A Porsche)
"One of the great enemies of design is when systems or objects become more complex than a person - or even a team of people - can keep in their heads. This is why software is generally beneath contempt." (Bran Ferren)
"Programming without an overall architecture or design in mind is like exploring a cave with only a flashlight: You don't know where you've been, you don't know where you're going, and you don't know quite where you are." (Danny Thorpe)
"The broader one’s understanding of the human experience, the better design we will have." (Steve Jobs)
"The essence of engineering consists not so much in the mere construction of the spectacular layouts or developments, but in the invention required - the analysis of the problem, the design, the solution by the mind which directs it all." (William Hood)
"The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise." (Edsger Dijkstra)
"The thing that makes software design difficult is that we must express thoughts about a problem and a solution we typically do not understand fully, using a language that does not contain many of our accustomed features of expression, to a system that is unforgiving of mistakes." (Alistair Cockburn)
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