diff -r 123f59618e87 -r 870693ce6ff0 devel-rules.rst --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/devel-rules.rst Mon Feb 22 13:34:55 2016 +0200 @@ -0,0 +1,594 @@ +.. -*- coding: utf-8; -*- +.. include:: HEADER.rst + +============================ + Software development rules +============================ +.. contents:: + :local: + +General discussion +================== + +See: + + http://en.wikipedia.org/wiki/List_of_software_development_philosophies + http://en.wikipedia.org/wiki/List_of_eponymous_laws + +Principle of good enough (POGE) +=============================== + +It favours quick-and-simple (but potentially extensible) designs over +elaborate systems designed by committees. + +Once the quick-and-simple design is deployed, it can then evolve as needed, +driven by user requirements. + +This kind of design is not appropriate in systems where it is not possible to +evolve the system over time, or where the full functionality is required from +the start. + +See: + + http://en.wikipedia.org/wiki/Principle_of_good_enough + +No Silver Bullet +================ + +There is no single development, in either technology or management technique, +which by itself promises even one order of magnitude improvement within a +decade in productivity, in reliability, in simplicity. + +See: + + http://en.wikipedia.org/wiki/No_Silver_Bullet + +Rule of thumb +============= + +A rule of thumb is a principle that postulate in some case use simple +procedure wich produce approximate result instead use complex but exact +produce. + +See: + + http://en.wikipedia.org/wiki/Rule_of_thumb + +The Zero One or Infinity +======================== + +The Zero One or Infinity (ZOI) rule is a rule of thumb in software design. It +suggests that arbitrary limits on the number of instances of a particular +entity should not be allowed. Specifically, that an entity should either be +forbidden entirely, one should be allowed, or any number (presumably, to the +limit of available storage) of them should be allowed. It should not be the +software that puts a hard limit on the number of instances of the entity. + + http://en.wikipedia.org/wiki/Zero_One_Infinity + +80-20 rule (pareto principle) +============================= + +This rule postulate that roughly 80% of the effects come from 20% of the +causes. + +This rule applied to optimisation (most time spent by program only by little +piece of code), functionality (80% of users use only 20% of program +functionality); bugs (fixing the top 20% of most reported bugs solve 80% of +the error and crashes). + +See: + + http://en.wikipedia.org/wiki/80:20_rule + +1% rule +======= + +The 1% rule states that the number of people who create content on the +internet represents approximately 1% (or less) of the people actually viewing +that content. + +See: + + http://en.wikipedia.org/wiki/1%25_rule_%28Internet_culture%29 + +Parkinson's Law +=============== + +Work expands so as to fill the time available for its completion. + +Data expands to fill the space available for storage. + +See: + + http://en.wikipedia.org/wiki/Parkinson%27s_law + +Ninety-ninety rule +================== + +The first 90% of the code accounts for the first 10% of the development time. +The remaining 10% of the code accounts for the other 90% of the development +time. + +See: + + http://en.wikipedia.org/wiki/Ninety-ninety_rule + +Wirth's law +=========== + +Software is getting slower more rapidly than hardware becomes faster. + +See: + + http://en.wikipedia.org/wiki/Wirth%27s_law + +Student syndrome +================ + +Student syndrome refers to the phenomenon that many people will start to fully +apply themselves to a task just at the last possible moment before a deadline. + +The student syndrome is a form of procrastination (). + +See: + + http://en.wikipedia.org/wiki/Student_syndrome + +Conway's Law +============ + +...organizations which design systems ... are constrained to produce designs +which are copies of the communication structures of these organizations. + +Example: Consider a two-person team of software engineers, A and B. Say A +designs and codes a software class X. Later, the team discovers that class X +needs some new features. If A adds the features, A is likely to simply expand X +to include the new features. If B adds the new features, B may be afraid of +breaking X, and so instead will create a new derived class X2 that inherits X's +features, and puts the new features in X2. So the final design is a reflection +of who implemented the functionality. + +A real life example: NASA's Mars Climate Orbiter crashed because one team used +United States customary units (e.g., inches, feet and pounds) while the other +used metric units for a key spacecraft operation. + +See: + + http://en.wikipedia.org/wiki/Conway%27s_Law + +Brooks's law +============ + +It takes some time for the people added to a project to become productive. + +Communication overheads increase as the number of people increases. + +Adding manpower to a late software project makes it later. + +See: + + http://en.wikipedia.org/wiki/Brooks%27_law + +Code bloat +========== + +Code bloat is the production of code that is perceived as unnecessarily long, +slow, or otherwise wasteful of resources. Code bloat generally refers to +source code size but sometimes is used to refer to the generated code size or +even the binary file size. + + http://en.wikipedia.org/wiki/Code_bloat + +Software bloat +============== + +Software bloat is a term used to describe the tendency of newer computer +programs to have a larger installation footprint, or have many unnecessary +features that are not used by end users, or just generally use more system +resources than necessary, while offering little or no benefit to its users. + + +Comparison of Microsoft Windows minimum hardware requirements (for 32-bit +versions): + +Windows version Processor Memory Hard disk +Windows 95[4] 25 MHz 4 MB ~50 MB +Windows 98[5] 66 MHz 16 MB ~200 MB +Windows 2000[6] 133 MHz 32 MB 650 MB +Windows XP[7] 233 MHz 64 MB 1.5 GB +Windows Vista[8] 800 MHz 512 MB 15 GB +Windows 7[9] 1 GHz 1 GB 16 GB + +.. epigraph:: + + Every program attempts to expand until it can read mail. Those programs which + cannot so expand are replaced by ones which can. + + -- Jamie Zawinski + +Second-system effect +==================== + +In computing, the second-system effect or sometimes the second-system syndrome +refers to the tendency, when following on from a relatively small, elegant, +and successful system, to design the successor as an elephantine, +feature-laden monstrosity. The term was first used by Fred Brooks in his +classic The Mythical Man-Month.[1] It described the jump from a set of simple +operating systems on the IBM 700/7000 series to OS/360 on the 360 series. + +Inner-platform effect +===================== + +The inner-platform effect is the tendency of software architects to create a +system so customizable as to become a replica, and often a poor replica, of +the software development platform they are using. + +XXX read more http://thedailywtf.com/Articles/The_Inner-Platform_Effect.aspx + + http://en.wikipedia.org/wiki/Inner-platform_effect + +Feature creep +============= + +Feature creep is the proliferation of features in a product such as computer +software. Extra features go beyond the basic function of the product and so +can result in baroque over-complication, or "featuritis", rather than simple, +elegant design. + + http://en.wikipedia.org/wiki/Feature_creep + +Bullet-point engineering +======================== + +Bullet-point engineering is a software design anti-pattern where developers +use the features of competing software packages as checklists of features to +implement in their own product. These features are often implemented poorly +and haphazardly, without any real design, merely so they can be added to a +bulleted list of features in marketing material. Bullet point engineering +often leads to feature creep and software bloat but may also simply result in +a poorly designed imitative product. + + http://en.wikipedia.org/wiki/Bullet-point_engineering + +KISS +==== + +Keep it simple and stupid, or keep it simple, stupid! + +Instruction creep and function creep, two instances of creeping featuritis, +are examples of failure to follow the KISS principle in software development. + + http://en.wikipedia.org/wiki/KISS_principle + +Minimalism +========== + +In computing, minimalism refers to the application of minimalist philosophies +and principles in hardware and software design and usage. + + http://en.wikipedia.org/wiki/Minimalism_%28computing%29 + +Unix philosophy +=============== + +.. epigraph:: + + "Do one thing and do it well." + + -- Doug McIlroy + +.. epigraph:: + + "Write programs that do one thing and do it well. Write programs to work + together. Write programs to handle text streams, because that is a universal + interface." + + -- Doug McIlroy + +.. epigraph:: + + #. You cannot tell where a program is going to spend its time. Bottlenecks + occur in surprising places, so do not try to second guess and put in a speed + hack until you've proven that's where the bottleneck is. + #. Measure. Do not tune for speed until your performance analysis tool tells + you which part of the code overwhelms the rest. + #. Fancy algorithms tend to run more slowly on small data sets than simple + algorithms. They tend to have a large constant factor in O(n) analysis, and + n is usually small. So don't get fancy unless Rule 2 indicates that n is big + enough. + #. Simplify your algorithms and data structures wherever it makes sense because + fancy algorithms are more difficult to implement without defects. The data + structures in most programs can be built from array lists, linked lists, + hash tables, and binary trees. + #. Data dominates. If you have chosen the right data structures and organized + things well, the algorithms will almost always be self-evident. Data + structures, not algorithms, are central to programming. + + -- Pike: Notes on Programming in C. + +.. epigraph:: + + 1. Small is beautiful. + 2. Make each program do one thing well. + 3. Build a prototype as soon as possible. + 4. Choose portability over efficiency. + 5. Store data in flat text files. + 6. Use software leverage to your advantage. + 7. Use shell scripts to increase leverage and portability. + 8. Avoid captive user interfaces. + 9. Make every program a filter. + + -- Mike Gancarz: The UNIX Philosophy + +With this not all agree: + + 1. Allow the user to tailor the environment. + 2. Make operating system kernels small and lightweight. + 3. Use lowercase and keep it short. + 4. Save trees. + 5. Silence is golden. + 6. Think parallel. + 7. The sum of the parts is greater than the whole. + 8. Look for the 90-percent solution. + 9. Worse is better. + 10. Think hierarchically. + + +** Misc. + +"Unix is simple. It just takes a genius to understand its simplicity." + -– Dennis Ritchie +"Unix never says 'please'." + -– Rob Pike + + http://en.wikipedia.org/wiki/Unix_philosophy + +Worse is better +=============== + +In the "Worse is better" design style, simplicity of both the interface and +the implementation is more important than any other attribute of the system — +including correctness, consistency and completeness. + +Simplicity + The design must be simple, both in implementation and interface. It is + more important for the implementation to be simpler than the interface. + Simplicity is the most important consideration in a design. +Correctness + The design must be correct in all observable aspects. It is slightly better + to be simple than correct. +Consistency + The design must not be overly inconsistent. Consistency can be sacrificed + for simplicity in some cases, but it is better to drop those parts of the + design that deal with less common circumstances than to introduce either + implementational complexity or inconsistency. +Completeness + The design must cover as many important situations as is practical. All + reasonably expected cases should be covered. Completeness can be sacrificed + in favor of any other quality. In fact, completeness must be sacrificed + whenever implementation simplicity is jeopardized. Consistency can be + sacrificed to achieve completeness if simplicity is retained; especially + worthless is consistency of interface. + + http://dreamsongs.com/WIB.html + Lisp: Good News, Bad News, How to Win Big + +The right thing +=============== + +The MIT approach (known as "The right thing"): + +Simplicity + The design must be simple, both in implementation and interface. It is + more important for the interface to be simpler than the implementation. +Correctness + The design must be correct in all observable aspects. Incorrectness is + simply not allowed. +Consistency + The design must be consistent. A design is allowed to be slightly less + simple and less complete to avoid inconsistency. Consistency is as important + as correctness. +Completeness + The design must cover as many important situations as is practical. All + reasonably expected cases must be covered. Simplicity is not allowed to + overly reduce completeness. + + http://dreamsongs.com/WIB.html + Lisp: Good News, Bad News, How to Win Big + +YAGNI +===== + +"You aren't gonna need it" (or YAGNI for short) is the principle in extreme +programming that programmers should not add functionality until it is +necessary. + + http://en.wikipedia.org/wiki/You_ain%27t_gonna_need_it + +DRY (DIE) +========= + +Don't Repeat Yourself (DRY) or Duplication is Evil (DIE). + + * VCS allow multiple and diverging copies ("branches"). + * Source code generation. + + http://en.wikipedia.org/wiki/Don%27t_repeat_yourself + +Do it yourself (DIY) +==================== + +Do it yourself (or DIY) is a term used to describe building, modifying, or +repairing of something without the aid of experts or professionals. + +when tasklist longer then people life mutch easy use already written libraries +then wrote own. + + http://en.wikipedia.org/wiki/Do_it_yourself + +Once and Only Once (OAOO) +========================= + +MoSCoW Method +============= + +The capital letters in MoSCoW stand for: + + * M - MUST have this (included in the current delivery timebox in order + for it to be a success). + * S - SHOULD have this if at all possible (critical to the success of the + project, but are not necessary for delivery in the current delivery + timebox). + * C - COULD have this if it does not affect anything else (nice to have). + * W - WON'T have this time but WOULD like in the future. + + http://en.wikipedia.org/wiki/MoSCoW_Method + +Separation of concerns +====================== + +In computer science, separation of concerns (SoC) is the process of separating +a computer program into distinct features that overlap in functionality as +little as possible. A concern is any piece of interest or focus in a program. +Typically, concerns are synonymous with features or behaviors. Progress +towards SoC is traditionally achieved through modularity of programming and +encapsulation (or "transparency" of operation), with the help of information +hiding. Layered designs in information systems are also often based on +separation of concerns (e.g., presentation layer, business logic layer, data +access layer, database layer). + +HyperText Markup Language (HTML) and cascading style sheets (CSS) are +languages intended to separate style from content. + + http://en.wikipedia.org/wiki/Separation_of_concerns + +Modular design +============== + +In systems engineering, modular design — or "modularity in design" — is an +approach that subdivides a system into smaller parts (modules) that can be +independently created and then used in different systems to drive multiple +functionalities. + + http://en.wikipedia.org/wiki/Modular_design + +Occam's razor +============= + +"entia non sunt multiplicanda praeter necessitatem" + +Entities must not be multiplied beyond necessity. + +Code and fix +============ + +Programmers immediately begin producing code. Bugs must be fixed before the +product can be shipped. + + http://en.wikipedia.org/wiki/Code_and_fix + +Cowboy coding +============= + +Cowboy coding is a term used to describe software development where the +developers have autonomy over the development process. This includes control +of the project's schedule, algorithms, tools, and coding style. + +A cowboy coder can be a lone developer or part of a group of developers with +either no external management or management that controls only non-development +aspects of the project, such as its nature, scope, and feature set (the +"what", but not the "how"). + + http://en.wikipedia.org/wiki/Cowboy_coding + +Extreme Programming +=================== + + http://en.wikipedia.org/wiki/Extreme_Programming + +Hollywood Principle +=================== + +In computer programming, the Hollywood Principle is stated as "don't call us, +we'll call you." It has applications in software engineering; see also +implicit invocation for a related architectural principle. + + http://en.wikipedia.org/wiki/Hollywood_Principle + +Inversion of control +==================== + +Inversion of control, or IoC, is an abstract principle describing an aspect of +some software architecture designs in which the flow of control of a system is +inverted in comparison to procedural programming. + + http://en.wikipedia.org/wiki/Inversion_of_control + +Literate programming +==================== + + http://en.wikipedia.org/wiki/Literate_Programming + +Model-driven architecture +========================= + + http://en.wikipedia.org/wiki/Model-driven_architecture + +Quick-and-dirty +=============== + +Quick-and-dirty is a term used in reference to anything that is an easy way to +implement a workaround or "kludge." Its usage is popular among programmers, +who use it to describe a crude solution or programming implementation that is +imperfect, inelegant, or otherwise inadequate, but which solves or masks the +problem at hand, and is generally faster and easier to put in place than a +proper solution. + + http://en.wikipedia.org/wiki/Quick-and-dirty + +Release early, release often +============================ + +Release early, release often (sometimes abbreviated RERO) is a software +development philosophy that emphasizes the importance of early and frequent +releases in creating a tight feedback loop between developers and testers or +users. + + http://en.wikipedia.org/wiki/Release_early,_release_often + +Test-driven development +======================= + +Test-driven development (TDD) is a software development technique that relies +on the repetition of a very short development cycle: First the developer +writes a failing automated test case that defines a desired improvement or new +function, then produces code to pass that test and finally refactors the new +code to acceptable standards. + + http://en.wikipedia.org/wiki/Test-driven_development + +Unified Process +=============== + +The Unified Software Development Process or Unified Process is a popular +iterative and incremental software development process framework. The +best-known and extensively documented refinement of the Unified Process is the +Rational Unified Process (RUP). + + http://en.wikipedia.org/wiki/Unified_Process + +Waterfall model +=============== + + 1. Requirements specification + 2. Design + 3. Construction (AKA implementation or coding) + 4. Integration + 5. Testing and debugging (AKA Validation) + 6. Installation + 7. Maintenance + + http://en.wikipedia.org/wiki/Waterfall_model + +* Do it yourself.