"A basic principle of data processing teaches the folly of trying to maintain independent files in synchronism. It is far better to combine them into one file with each record containing all the information both files held concerning a given key." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"A baseball manager recognizes a nonphysical talent, hustle, as an essential gift of great players and great teams. It is the characteristic of running faster than necessary, moving sooner than necessary, trying harder than necessary. It is essential for great programming teams, too. Hustle provides the cushion, the reserve capacity, that enables a team to cope with routine mishaps, to anticipate and forfend minor calamities. The calculated response, the measured effort, are the wet blankets that dampen hustle. As we have seen, one must get excited about a one-day slip. Such are the elements of catastrophe." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"A computer program is a message from a man to a machine. The rigidly marshaled syntax and the scrupulous definitions all exist to make intention clear to the dumb engine." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"A good information system both exposes interface errors and stimulates their correction" (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"A good top-down design avoids bugs in several ways. First, the clarity of structure and representation makes the precise statement of requirements and functions of the modules easier. Second, the partitioning and independence of modules avoids system bugs. Third, the suppression of detail makes flaws in the structure more apparent. Fourth, the design can be tested at each of its refinement steps, so testing can start earlier and focus on the proper level of detail at each step." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
[Brook's Law:] "Adding manpower to a late software project makes it later." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"All programmers are optimists. [...] Computer programming, however, creates with an exceedingly tractable medium. The programmer builds from pure thought-stuff: concepts and very flexible representations thereof. Because the medium is tractable, we expect few difficulties in implementation; hence our pervasive optimism. Because our ideas are faulty, we have bugs; hence our optimism is unjustified." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Because ease of use is the purpose, this ratio of function to conceptual complexity is the ultimate test of system design. Neither function alone nor simplicity alone defines a good design. [...] Function, and not simplicity, has always been the measure of excellence for its designers." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"By the architecture of a system, I mean the complete and detailed specification of the user interface. For a computer this is the programming manual. For a compiler it is the language manual. For a control program it is the manuals for the language or languages used to invoke its functions. For the entire system it is the union of the manuals the user must consult to do his entire job." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Clearly, methods of designing programs so as to eliminate or at least illuminate side effects can have an immense payoff in maintenance costs. So can methods of implementing designs with fewer people, fewer interfaces, and hence fewer bugs." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Conceptual integrity is the most important consideration in system design. [,..] For a given level of function, however, that system is best in which one can specify things with the most simplicity and straightforwardness. Simplicity is not enough. [...] Simplicity and straightforwardness proceed from conceptual integrity. Every part must reflect the same philosophies and the same balancing of desiderata. Every part must even use the same techniques in syntax and analogous notions in semantics. Ease of use, then, dictates unity of design, conceptual integrity." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Different levels of documentation are required for the casual user of a program, for the user who must depend upon a program, and for the user who must adapt a program for changes in circumstance or purpose." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Failure to allow enough time for system test, in particular, is peculiarly disastrous. Since the delay comes at the end of the schedule, no one is aware of schedule trouble until almost the delivery date. Bad news, late and without warning, is unsettling to customers and to managers." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Far be it from me to suggest that all changes in customer objectives and requirements must, can, or should be incorporated in the design. Clearly a threshold has to be established, and it must get higher and higher as development proceeds, or no product ever appears." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Flow charts show the decision structure of a program, which is only one aspect of its structure. They show decision structure rather elegantly when the flow chart is on one page, but the overview breaks down badly when one has multiple pages, sewed together with numbered exits and connectors." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"How does one control a big project on a tight schedule? The first step is to have a schedule." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"I will contend that conceptual integrity is the most important consideration in system design. It is better to have a system omit certain anomalous features and improvements, but to reflect one set of design ideas, than to have one that contains many good but independent and uncoordinated ideas." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"It is very difficult to make a vigorous, plausible, and jobrisking defense of an estimate that is derived by no quantitative method, supported by little data, and certified chiefly by the hunches of the managers." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Men and months are interchangeable commodities only when a task can be partitioned among many workers with no communication among them. This is true of reaping wheat or picking cotton; it is not even approximately true of systems programming." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"More software projects have gone awry for lack of calendar time than for all other causes combined. Why is this cause of disaster so common?
First, our techniques of estimating are poorly developed. More seriously, they reflect an unvoiced assumption which is quite untrue, i.e., that all will go well. Second, our estimating techniques fallaciously confuse effort with progress, hiding the assumption that men and months are interchangeable. Third, because we are uncertain of our estimates, software managers often lack the courteous stubbornness of Antoine's chef. Fourth, schedule progress is poorly monitored. Techniques proven and routine in other engineering disciplines are considered radical innovations in software engineering. Fifth, when schedule slippage is recognized, the natural (and traditional) response is to add manpower." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Much more often, strategic breakthrough will come from redoing the representation of the data or tables. This is where the heart of a program lies. [...] Representation is the essence of programming." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Nevertheless, some changes in objectives are inevitable, and it is better to be prepared for them than to assume that they won't come. Not only are changes in objective inevitable, changes in development strategy and technique are also inevitable. The throw-one-away concept is itself just an acceptance of the fact that as one learns, he changes the design." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"No amount of space budgeting and control can make a program small. That requires invention and craftsmanship. [...] Beyond craftsmanship lies invention, and it is here that lean, spare, fast programs are born. Almost always these are the result of stategic breakthrough rather than tactical cleverness." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Of course the technological base on which one builds is always advancing. As soon as one freezes a design, it becomes obsolete in terms of its concepts. But implementation of real products demands phasing and quantizing. The obsolescence of an implementation must be measured against other existing implementations, not against unrealized concepts. The challenge and the mission are to find real solutions to real problems on actual schedules with available resources." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"[...] on the larger project each of the roles is necessarily a full-time job, or more." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Program maintenance involves no cleaning, lubrication, or repair of deterioration. It consists chiefly of changes that repair design defects. Much more often than with hardware, these changes include added functions. Usually they are visible to the user." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Programming then is fun because it gratifies creative longings built deep within us and delights sensibilities we have in common with all men." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Structuring an organization for change is much harder than designing a system for change. Each man must be assigned to jobs that broaden him, so that the whole force is technically flexible. [...] Management structures also need to be changed as the system changes." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Systems program building is an entropy-decreasing process, hence inherently metastable. Program maintenance is an entropy-increasing process, and even its most skillful execution only delays the subsidence of the system into unfixable obsolescence." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The added burden of communication is made up of two parts, training and intercommunication. Each worker must be trained in the technology, the goals of the effort, the overall strategy, and the plan of work. This training cannot be partitioned, so this part of the added effort varies linearly with the number of workers." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The boss must first distinguish between action information and status information. He must discipline himself not to act on problems his managers can solve, and never to act on problems when he is explicitly reviewing status." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The flow chart is a most thoroughly oversold piece of program documentation. Many programs don't need flow charts at all; few programs need more than a one-page flow chart. [...] In fact, flow charting is more preached than practiced." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The fundamental problem with program maintenance is that fixing a defect has a substantial (20-50 percent) chance of introducing another. So the whole process is two steps forward and one step back." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The hardest single part of building a software system
is deciding precisely what to build."
"The means by which communication is obviated are division of labor and specialization of function." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds his castles in the air, from air, creating by exertion of the imagination. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures. […] Yet the program construct, unlike the poet's words, is real in the sense that it moves and works, producing visible outputs separate from the construct itself. […] The magic of myth and legend has come true in our time. One types the correct incantation on a keyboard, and a display screen comes to life, showing things that never were nor could be." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The project workbook is not so much a separate document as it is a structure imposed on the documents that the project will be producing anyway. [...] The early design of the project workbook ensures that the documentation structure itself is crafted, not haphazard. [...] The second reason for the project workbook is control of the distribution of information. The problem is not to restrict information, but to ensure that relevant information gets to all the people who need it." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The purpose of a programming system is to make a computer easy to use. To do this, it furnishes languages and various facilities that are in fact programs invoked and controlled by language features. But these facilities are bought at a price: the external description of a programming system is ten to twenty times as large as the external description of the computer system itself. The user finds it far easier to specify any particular function, but there are far more to choose from, and far more options and formats to remember." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The second fallacious thought mode is expressed in the very unit of effort used in estimating and scheduling: the man-month. Cost does indeed vary as the product of the number of men and the number of months. Progress does not. Hence the man-month as a unit for measuring the size of a job is a dangerous and deceptive myth. It implies that men and months are interchangeable." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The programmer's primary weapon in the never-ending battle against slow system is to change the intramodular structure. Our first response should be to reorganize the modules' data structures." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The separation of architectural effort from implementation is a very powerful way of getting conceptual integrity on very large projects." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The solution, I think, is to merge the files, to incorporate the documentation in the source program. This is at once a powerful incentive toward proper maintenance, and an insurance that the documentation will always be handy to the program user. Such programs are called self-documenting." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The task of the manager is to develop a plan and then to realize it. But only the written plan is precise and communicable. Such a plan consists of documents on what, when, how much, where, and who. This small set of critical documents encapsulates much of the manager's work. If their comprehensive and critical nature is recognized in the beginning, the manager can approach them as friendly tools rather than annoying busywork. He will set his direction much more crisply and quickly by doing so." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Thinkers are rare; doers are rarer; and thinker-doers are rarest." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Why is programming fun? What delights may its practitioner expect as his reward?
First is the sheer joy of making things. As the child delights in his mud pie, so the adult enjoys building things, especially things of his own design. [...] Second is the pleasure of making things that are useful to other people. Deep within, we want others to use our work and to find it helpful. [...] Third is the fascination of fashioning complex puzzle-like objects of interlocking moving parts and watching them work in subtle cycles, playing out the consequences of principles built in from the beginning. [...] Fourth is the joy of always learning, which springs from the nonrepeating nature of the task. [...] Finally, there is the delight of working in such a tractable medium." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Yet the program construct, unlike the poet's words, is real in the sense that it moves and works, producing visible outputs separate from the construct itself. It prints results, draws pictures, produces sounds, moves arms. The magic of myth and legend has come true in our time. One types the correct incantation on a keyboard, and a display screen comes to life, showing things that never were nor could be."
"Einstein repeatedly argued that there must be
simplified explanations of nature, because God is not capricious or arbitrary.
No such faith comforts the software engineer. Much of the complexity he must
master is arbitrary complexity [… ] because they were designed by different
people, rather than by God." (Fred Brooks, "No Silver Bullet",
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", 1986)
"The essence of a software entity is a construct of interlocking concepts: […] I believe the hard part of building software to be the specification, design, and testing of this conceptual construct, not the labor of representing it and testing the fidelity of the representation." (Fred Brooks, "No Silver Bullet", 1986)
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