Deprecation is the discouragement of use of something human-made, such as a linguisticterm, aproper name, a feature,design, functionality, piece of code, or practice. Typically a thing previously used is deprecated because it is—or is claimed or thought to be—inferior compared to other options now available. Deprecation is thus a mechanism for future improvement. Deprecation implies that thecommunity (generally, or acommunity of experts, or aprofessional body governing asector orindustry) has determined that future use—of the term, name, device, design, or feature—is unwise. However, it also means its replacement or removal is not required or is non-urgent.
Something may be deprecated even though past or extant applications of it might still be useful or functional in particular contexts—the goal here need not be the complete replacement of that which has been deprecated but rather an improvement on some broad metric (eg, safety) of thestock of that thing over time. Thus: deprecation of archaic terms to obtain consistency and readability inlanguage/terminology; deprecation ofobsolete electrical components to improvesafety andcompatibility in thehousing stock; or deprecation of certain sharedcode to improve anopen-source software project.[1]
Deprecation typically implies or foreshadows a phasing out, a withdrawal or removal from availability, or a discontinuance of use orsupport, at some time in the future.
In general English usage, the verb "todeprecate" means "to express disapproval of (something)". It derives from theLatindeponent verbdeprecari, meaning "to ward off (adisaster) by prayer".
An early, documented usage of "deprecate" in the relevant sense is inUsenet posts in 1984, referring to obsolete features in4.2BSD and theCprogramming language.[2] An expanded definition of "deprecate" was cited in theJargon File in its 1991 revision,[3] and similar definitions are found in commercial software documentation from 2014[1] and 2023.[4]
Deprecation is animprovement mechanism commonly used in software development, particularly where projects involve a large community of users orcoders, or have long or complexdevelopment histories, or are rapidly iterating (thus generating more supersedence).
While a deprecated software feature remains in the software, its use may raise warning messages recommending alternatives or alternative practices. Deprecated status may also indicate the feature will be removed in the future. Features are deprecated, rather than immediately removed, to providebackward compatibility and to give programmers time to bring affected code into compliance with a new standard.
Notable reasons for deprecation include:
| Reason | Example(s) |
|---|---|
| The feature has been replaced by a more powerful alternative feature. | TheLinux kernel contains two modules to communicate withWindows networks:smbfs andcifs. The latter provides better security, supports more protocol features, and integrates better with the rest of the kernel. Since the inclusion ofcifs,smbfs has been deprecated.[5] |
| The feature contains a design flaw, frequently a security flaw, and so should be avoided, but existing code depends upon it. |
|
| The feature is considered extraneous and will be removed in a planned future version. | Early versions of theWebmarkup languageHTML included aFONT element to allow page designers to specify thefont in which text should be displayed. With the release ofCascading Style Sheets and HTML 4.0, theFONT element became extraneous, and detracted from the benefits of noting structural markup in HTML and graphical formatting in CSS. Thus, theFONT element was deprecated in theTransitional HTML 4.0 standard, and eliminated in theStrict variant.[8] |
| A planned future version of the software will make major structural changes, making it impossible or impractical to support older features. | WhenApple Inc. planned the transition fromMac OS 9 toMac OS X, it created asubset of the older system'sAPI which would support most programs with minor changes: theCarbon library (which has since been deprecated itself), available in both Mac OS 9 and Mac OS X. Programmers who were, at the time, chiefly using Mac OS 9, could ensure that their programs would run natively on Mac OS X by using only the API functions supported in Carbon. Other Mac OS 9 functions were deprecated, and were never supported natively in Mac OS X.[9] |
| Naming consistency. | AnAPI may inconsistently mix spellings such as "color" and "colour" as a result of different developers using different spellings. To enforce consistency, all identifiers using one spelling would be duplicated for[clarification needed] the other spelling and identifiers using the unfavored spelling deprecated. |
| A feature that once was available independently is combined with its co-feature. | InVLC Media Player, VLC used to stand for "VideoLan Client", and a separate "VideoLan Server" was available as its co-feature. Both the client and server became available in the same package, and so getting one independently would be impractical.[10] |
Abuilding code example is the use ofungrounded ("2-prong") electrical receptacles (UK English: "unearthed"). Over time, these older devices were widely deprecated in favor of safer grounded ("3-prong") receptacles. The older, ungrounded receptacles were still permitted in many places by "grandfathering" them in existingelectrical wiring, while prohibiting them for new installations. Sales and usage of ungrounded receptacles thus declined; and, if they were even still available for legal purchase in a location, they would be seen as obsolete, and would generally be intended only for repairs to existing, older electrical installations.
Intechnical standards, use of a certain clause may be discouraged or superseded by new clauses. As an example, in theEthernet standardIEEE 802.3-2012, parts of Clause 5 (Layer Management) are deprecated or superseded by Clause 30 (Management).
In writing andediting, usage of a word may be deprecated because it is ambiguous, confusing, or offensive to audiences or certain members thereof. For example, the wordssanction andinflammable may be misinterpreted because they haveauto-antonymic or self-contradictory meanings; writing style guides often recommend substituting other words that are clearly understood and unambiguous. Some words, or word usages (meanings), that have acquired different connotations over time (such asgay, orcolored), may be deprecated to avoid issues (or distraction) due to ambiguity, obsolescence or offense.
Deprecation may also occur when a technical or scientific term becomes incorrect orobsolete, either through change or supersession or further scientific discovery or the development of new scientific consensus.[clarification needed] An example frompaleontology is the previous (and now discontinued) deprecation of the termBrontosaurus in favor of the genusApatosaurus (which Brontosaurus was, for a time, thought to be a part of).[11][12]
Some deprecated terms in medicine areconsumption (tuberculosis),grippe (influenza), andapoplexy (stroke). Superseded or misleading names of medical conditions or diseases are often deprecated, in order to avoid confusion, stigma, or misunderstandings about their risks (eg, "gay related immune deficiency syndrome", the initial term for HIV-AIDS, was erroneous and discriminatory and quickly deprecated).
Inchemical nomenclature, the international standards organizationIUPAC (International Union of Pure and Applied Chemistry) has deprecated the term "methyl ethyl ketone", and now recommends using the term "ethyl methyl ketone" instead.[13]
Deprecated function: char * gets (char *s). ... Thegetsfunction isvery dangerous because it provides no protection against overflowing the strings. The GNU library includes it for compatibility only. You shouldalways usefgetsorgetlineinstead.
