An anti-pattern is a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by Andrew Koenig, was inspired by a book, Design Patterns, which highlights a number of design patterns in software development that its authors considered to be highly reliable and effective.
The term was popularized three years later by the book AntiPatterns, which extended its use beyond the field of software design to refer informally to any commonly reinvented but bad solution to a problem. Examples include analysis paralysis, cargo cult programming, death march, groupthink and vendor lock-in.
According to the authors of Design Patterns, there must be at least two key elements present to formally distinguish an actual anti-pattern from a simple bad habit, bad practice, or bad idea:
- A commonly used process, structure or pattern of action that despite initially appearing to be an appropriate and effective response to a problem, typically has more bad consequences than good ones
- Another solution exists that is documented, repeatable and proven to be effective.
Analysis paralysis: A project stalled in the analysis phase, unable to achieve support for any of the potential plans of approachBicycle shed: Giving disproportionate weight to trivial issuesBleeding edge: Operating with cutting-edge technologies that are still untested and/or unstable, leading to cost overruns, under-performance, and/or delayed deliveryBystander apathy: The phenomenon in which people are less likely to or do not offer help to a person in need when others are presentCash cow: A profitable legacy product that often leads to complacency about new productsDesign by committee: The result of having many contributors to a design, but no unifying visionEscalation of commitment: Failing to revoke a decision when it proves wrongGroupthink: A collective state where group members begin to (often unknowingly) think alike and reject differing viewpointsManagement by objectives: Management by numbers, focus exclusively on quantitative management criteria, when these are non-essential or cost too much to acquireMicromanagement: Ineffectiveness from excessive observation, supervision, or other hands-on involvement from managementMoral hazard: Insulating a decision-maker from the consequences of his or her decisionMushroom management: Keeping employees "in the dark and fed manure" (also "left to stew and finally canned")Peter principle: Continually promoting otherwise well-performing employees up to their level of incompetence, where they remain indefinitelySeagull management: Management in which managers only interact with employees when a problem arises, when they "fly in, make a lot of noise, dump on everyone, do not solve the problem, then fly out"Stovepipe or Silos: An organizational structure of isolated or semi-isolated teams, in which too many communications take place up and down the hierarchy, rather than directly with other teams across the organizationTypecasting: Locking successful employees into overly safe, narrowly defined, predictable roles based on their past successes rather than their potentialVendor lock-in: Making a system excessively dependent on an externally supplied componentCivic Ignorance: Group or person ignores or misrepresents civic ideas, problems, or solutionsViolence: Achieving social dominance and submission through violenceEnvironmental Degradation: degrading the natural environment helps cause inequality, disease, misery, social unrestCart before the horse: Focusing too many resources on a stage of a project out of its sequenceDeath march: A project whose staff, while expecting it to fail, are compelled to continue, often with much overwork, by management which is in denialNinety-ninety rule: Tendency to underestimate the amount of time to complete a project when it is "nearly done"Overengineering: Spending resources making a project more robust and complex than is neededScope creep: Uncontrolled changes or continuous growth in a project’s scope, or adding new features to the project after the original requirements have been drafted and accepted (also known as requirement creep and feature creep)Smoke and mirrors: Demonstrating unimplemented functions as if they were already implementedBrooks' law: Adding more resources to a project to increase velocity, when the project is already slowed down by coordination overhead.Abstraction inversion: Not exposing implemented functionality required by callers of a function/method/constructor, so that the calling code awkwardly re-implements the same functionality in terms of those callsAmbiguous viewpoint: Presenting a model (usually Object-oriented analysis and design (OOAD)) without specifying its viewpointBig ball of mud: A system with no recognizable structureDatabase-as-IPC: Using a database as the message queue for routine interprocess communication where a much more lightweight mechanism would be suitableGold plating: Continuing to work on a task or project well past the point at which extra effort is adding valueInner-platform effect: A system so customizable as to become a poor replica of the software development platformInput kludge: Failing to specify and implement the handling of possibly invalid inputInterface bloat: Making an interface so powerful that it is extremely difficult to implementMagic pushbutton: A form with no dynamic validation, or input assistance such as dropdownsRace hazard: Failing to see the consequences of events that can sometimes interfere with each otherStovepipe system: A barely maintainable assemblage of ill-related componentsAnemic domain model: The use of the domain model without any business logic. The domain model's objects cannot guarantee their correctness at any moment, because their validation and mutation logic is placed somewhere outside (most likely in multiple places). Martin Fowler considers this to be an anti-pattern, but some disagree that it is always an anti-pattern.BaseBean: Inheriting functionality from a utility class rather than delegating to itCall super: Requiring subclasses to call a superclass's overridden methodCircle-ellipse problem: Subtyping variable-types on the basis of value-subtypesCircular dependency: Introducing unnecessary direct or indirect mutual dependencies between objects or software modulesConstant interface: Using interfaces to define constantsGod object: Concentrating too many functions in a single part of the design (class)Object cesspool: Reusing objects whose state does not conform to the (possibly implicit) contract for re-useObject orgy: Failing to properly encapsulate objects permitting unrestricted access to their internalsPoltergeists: Objects whose sole purpose is to pass information to another objectSequential coupling: A class that requires its methods to be called in a particular orderYo-yo problem: A structure (e.g., of inheritance) that is hard to understand due to excessive fragmentationAccidental complexity: Programming tasks which could be eliminated with better tools (as opposed to essential complexity inherent in the problem being solved)Action at a distance: Unexpected interaction between widely separated parts of a systemBoat anchor: Retaining a part of a system that no longer has any useBusy waiting: Consuming CPU while waiting for something to happen, usually by repeated checking instead of messagingCaching failure: Forgetting to clear a cache that holds a negative result (error) after the error condition has been correctedCargo cult programming: Using patterns and methods without understanding whyCoding by exception: Adding new code to handle each special case as it is recognizedDesign pattern: The use of patterns has itself been called an anti-pattern, a sign that a system is not employing enough abstractionError hiding: Catching an error message before it can be shown to the user and either showing nothing or showing a meaningless message. This anti-pattern is also named Diaper Pattern. Also can refer to erasing the Stack trace during exception handling, which can hamper debugging.Hard code: Embedding assumptions about the environment of a system in its implementationLasagna code: Programs whose structure consists of too many layersLava flow: Retaining undesirable (redundant or low-quality) code because removing it is too expensive or has unpredictable consequencesLoop-switch sequence: Encoding a set of sequential steps using a switch within a loop statementMagic numbers: Including unexplained numbers in algorithmsMagic strings: Implementing presumably unlikely input scenarios, such as comparisons with very specific strings, to mask functionality.Repeating yourself: Writing code which contains repetitive patterns and substrings over again; avoid with once and only once (abstraction principle)Shotgun surgery: Developer adds features to an application codebase which span a multiplicity of implementors or implementations in a single changeSoft code: Storing business logic in configuration files rather than source codeSpaghetti code: Programs whose structure is barely comprehensible, especially because of misuse of code structuresSuperstitious coding: Coding to handle error conditions which are already known to be impossible.Copy and paste programming: Copying (and modifying) existing code rather than creating generic solutionsGolden hammer: Assuming that a favorite solution is universally applicable (See: Silver bullet)Improbability factor: Assuming that it is improbable that a known error will occurNot Invented Here (NIH) syndrome: The tendency towards reinventing the wheel (failing to adopt an existing, adequate solution)Invented here: The tendency towards dismissing any innovation or less than trivial solution originating from inside the organization, usually because of lack of confidence in the staffPremature optimization: Coding early-on for perceived efficiency, sacrificing good design, maintainability, and sometimes even real-world efficiencyProgramming by permutation (or "programming by accident", or "programming by coincidence"): Trying to approach a solution by successively modifying the code to see if it worksReinventing the square wheel: Failing to adopt an existing solution and instead adopting a custom solution which performs much worse than the existing oneSilver bullet: Assuming that a favorite technical solution can solve a larger process or problemTester Driven Development: Software projects in which new requirements are specified in bug reportsEvery Fool His Own Tool: Failing to use proper software development principles when creating tools to facilitate the software development process itself.Dependency hell: Problems with versions of required productsDLL hell: Inadequate management of dynamic-link libraries (DLLs), specifically on Microsoft WindowsExtension conflict: Problems with different extensions to classic Mac OS attempting to patch the same parts of the operating systemJAR hell: Overutilization of multiple JAR files, usually causing versioning and location problems because of misunderstanding of the Java class loading model