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--- | ||
title: Versionamento Semântico 1.0.0-beta | ||
language: pt-BR | ||
--- | ||
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Versionamento Semântico 1.0.0-beta | ||
================================== | ||
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No mundo de gerenciamento de software existe algo terrível conhecido como | ||
inferno das dependências ("dependency hell"). Quanto mais o sistema cresce, e | ||
mais pacotes são adicionados a ele, maior será a possibilidade de, um dia, você | ||
encontrar-se neste poço de desespero. | ||
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Em sistemas com muitas dependências, lançar novos pacotes de versões pode se | ||
tornar rapidamente um pesadelo. Se as especificações das dependências são muito | ||
amarradas você corre o risco de um bloqueio de versão (A falta de capacidade de | ||
atualizar um pacote sem ter de liberar novas versões de cada pacote dependente). | ||
Se as dependências são vagamente especificadas, você irá inevitavelmente ser | ||
mordido pela 'promiscuidade da versão' (assumindo compatibilidade com futuras | ||
versões mais do que é razoável). O inferno das dependências é onde você está | ||
quando um bloqueio de versão e/ou promiscuidade de versão te impede de seguir | ||
em frente com seu projeto de maneira fácil e segura. | ||
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Como uma solução para este problema proponho um conjunto simples de regras e | ||
requisitos que ditam como os números das versões são atribuídos e incrementados. | ||
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Para que este sistema funcione, primeiro você precisa declarar uma API pública. | ||
Isto pode consistir de documentação ou ser determinada pelo próprio código. De | ||
qualquer maneira, é importante que esta API seja clara e precisa. Depois de | ||
identificada a API pública, você comunica as mudanças com incrementos | ||
específicos para o seu número de versão. Considere o formato de versão X.Y.Z | ||
(Maior.Menor.Correção). Correção de falhas (bug fixes) que não afetam a API, | ||
incrementa a versão de Correção, adições/alterações compatíveis com as versões | ||
anteriores da API incrementa a versão Menor, e alterações incompatíveis com as | ||
versões anteriores da API incrementa a versão Maior. | ||
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Eu chamo esse sistema de "Versionamento Semântico". Sob este esquema, os números | ||
de versão e a forma como eles mudam, transmite o significado do código | ||
subjacente e o que foi modificado de uma versão para a próxima. | ||
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Especificação de Versionamento Semântico (SemVer) | ||
------------------------------------------------- | ||
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As palavras-chaves "DEVE", "NÃO DEVE", "OBRIGATÓRIO", "DEVERÁ", "NÃO DEVERÁ", | ||
"DEVERIA", "NÃO DEVERIA", "RECOMENDADO", "PODE" e "OPCIONAL" no presente | ||
documento devem ser interpretados como descrito na RFC 2119. | ||
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1. Software usando Versionamento Semântico DEVE declarar uma API pública. Esta | ||
API poderá ser declarada no próprio código ou existir estritamente na | ||
documentação, desde que seja precisa e compreensiva. | ||
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1. Um número de versão normal DEVE ter o formato de X.Y.Z, onde X, Y, e Z são | ||
inteiros. X é a versão Maior, Y é a versão Menor, e Z é a versão de Correção. | ||
Cada elemento DEVE aumentar numericamente por incrementos de um. | ||
Por exemplo: 1.9.0 -> 1.10.0 -> 1.11.0. | ||
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1. Quando o número de uma versão maior for incrementado, a versão menor e a | ||
versão de correção DEVEM ser reinicializadas para 0 (zero). Quando o número de | ||
uma versão menor foi incrementado, a versão de correção DEVE ser reinicializada | ||
como 0 (zero). Por exemplo: 1.1.3 -> 2.0.0 e 2.1.7 -> 2.2.0. | ||
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1. A pre-release version number MAY be denoted by appending an arbitrary | ||
string immediately following the patch version and a decimal point. The string | ||
MUST be comprised of only alphanumerics plus dash [0-9A-Za-z-] and MUST begin | ||
with an alpha character [A-Za-z]. Pre-release versions satisfy but have a | ||
lower precedence than the associated normal version. Precedence SHOULD be | ||
determined by lexicographic ASCII sort order. For instance: 1.0.0.alpha1 < | ||
1.0.0.beta1 < 1.0.0.beta2 < 1.0.0.rc1 < 1.0.0. | ||
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1. Once a versioned package has been released, the contents of that version | ||
MUST NOT be modified. Any modifications must be released as a new version. | ||
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1. Major version zero (0.y.z) is for initial development. Anything may change | ||
at any time. The public API should not be considered stable. | ||
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1. Version 1.0.0 defines the public API. The way in which the version number | ||
is incremented after this release is dependent on this public API and how it | ||
changes. | ||
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1. Patch version Z (x.y.Z | x > 0) MUST be incremented if only backwards | ||
compatible bug fixes are introduced. A bug fix is defined as an internal | ||
change that fixes incorrect behavior. | ||
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1. Minor version Y (x.Y.z | x > 0) MUST be incremented if new, backwards | ||
compatible functionality is introduced to the public API. It MAY be | ||
incremented if substantial new functionality or improvements are introduced | ||
within the private code. It MAY include patch level changes. | ||
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1. Major version X (X.y.z | X > 0) MUST be incremented if any backwards | ||
incompatible changes are introduced to the public API. It MAY include minor | ||
and patch level changes. | ||
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Tagging Specification (SemVerTag) | ||
--------------------------------- | ||
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This sub-specification SHOULD be used if you use a version control system | ||
(Git, Mercurial, SVN, etc) to store your code. Using this system allows | ||
automated tools to inspect your package and determine SemVer compliance and | ||
released versions. | ||
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1. When tagging releases in a version control system, the tag for a version | ||
MUST be "vX.Y.Z" e.g. "v3.1.0". | ||
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1. The first revision that introduces SemVer compliance SHOULD be tagged | ||
"semver". This allows pre-existing projects to assume compliance at any | ||
arbitrary point and for automated tools to discover this fact. | ||
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Why Use Semantic Versioning? | ||
---------------------------- | ||
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This is not a new or revolutionary idea. In fact, you probably do something | ||
close to this already. The problem is that "close" isn't good enough. Without | ||
compliance to some sort of formal specification, version numbers are | ||
essentially useless for dependency management. By giving a name and clear | ||
definition to the above ideas, it becomes easy to communicate your intentions | ||
to the users of your software. Once these intentions are clear, flexible (but | ||
not too flexible) dependency specifications can finally be made. | ||
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A simple example will demonstrate how Semantic Versioning can make dependency | ||
hell a thing of the past. Consider a library called "Firetruck." It requires a | ||
Semantically Versioned package named "Ladder." At the time that Firetruck is | ||
created, Ladder is at version 3.1.0. Since Firetruck uses some functionality | ||
that was first introduced in 3.1.0, you can safely specify the Ladder | ||
dependency as greater than or equal to 3.1.0 but less than 4.0.0. Now, when | ||
Ladder version 3.1.1 and 3.2.0 become available, you can release them to your | ||
package management system and know that they will be compatible with existing | ||
dependent software. | ||
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As a responsible developer you will, of course, want to verify that any | ||
package upgrades function as advertised. The real world is a messy place; | ||
there's nothing we can do about that but be vigilant. What you can do is let | ||
Semantic Versioning provide you with a sane way to release and upgrade | ||
packages without having to roll new versions of dependent packages, saving you | ||
time and hassle. | ||
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If all of this sounds desirable, all you need to do to start using Semantic | ||
Versioning is to declare that you are doing so and then follow the rules. Link | ||
to this website from your README so others know the rules and can benefit from | ||
them. | ||
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FAQ | ||
--- | ||
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### How do I know when to release 1.0.0? | ||
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If your software is being used in production, it should probably already be | ||
1.0.0. If you have a stable API on which users have come to depend, you should | ||
be 1.0.0. If you're worrying a lot about backwards compatibility, you should | ||
probably already be 1.0.0. | ||
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### Doesn't this discourage rapid development and fast iteration? | ||
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Major version zero is all about rapid development. If you're changing the API | ||
every day you should either still be in version 0.x.x or on a separate | ||
development branch working on the next major version. | ||
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### If even the tiniest backwards incompatible changes to the public API require a major version bump, won't I end up at version 42.0.0 very rapidly? | ||
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This is a question of responsible development and foresight. Incompatible | ||
changes should not be introduced lightly to software that has a lot of | ||
dependent code. The cost that must be incurred to upgrade can be significant. | ||
Having to bump major versions to release incompatible changes means you'll | ||
think through the impact of your changes, and evaluate the cost/benefit ratio | ||
involved. | ||
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### Documenting the entire public API is too much work! | ||
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It is your responsibility as a professional developer to properly document | ||
software that is intended for use by others. Managing software complexity is a | ||
hugely important part of keeping a project efficient, and that's hard to do if | ||
nobody knows how to use your software, or what methods are safe to call. In | ||
the long run, Semantic Versioning, and the insistence on a well defined public | ||
API can keep everyone and everything running smoothly. | ||
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### What do I do if I accidentally release a backwards incompatible change as a minor version? | ||
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As soon as you realize that you've broken the Semantic Versioning spec, fix | ||
the problem and release a new minor version that corrects the problem and | ||
restores backwards compatibility. Remember, it is unacceptable to modify | ||
versioned releases, even under this circumstance. If it's appropriate, | ||
document the offending version and inform your users of the problem so that | ||
they are aware of the offending version. | ||
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### What should I do if I update my own dependencies without changing the public API? | ||
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That would be considered compatible since it does not affect the public API. | ||
Software that explicitly depends on the same dependencies as your package | ||
should have their own dependency specifications and the author will notice any | ||
conflicts. Determining whether the change is a patch level or minor level | ||
modification depends on whether you updated your dependencies in order to fix | ||
a bug or introduce new functionality. I would usually expect additional code | ||
for the latter instance, in which case it's obviously a minor level increment. | ||
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About | ||
----- | ||
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The Semantic Versioning specification is authored by [Tom Preston-Werner](http://tom.preston-werner.com), inventor of Gravatars and cofounder of GitHub. | ||
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If you'd like to leave feedback, please [open an issue on GitHub](https://github.com/mojombo/semver.org/issues). | ||
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License | ||
------- | ||
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Creative Commons ― CC BY 3.0 | ||
http://creativecommons.org/licenses/by/3.0/ |