Maintaining and upgrading software without breaking dependencies is crucial for both developers and users. Semantic Versioning, often abbreviated as SemVer, provides a structured format to version software in a way that avoids compatibility issues. This post will explore what semantic versioning is, why it’s beneficial, and how to use it effectively in your projects.

What is semantic versioning?

Semantic versioning is a versioning scheme that reflects changes in software in a predictable manner. It helps in managing the dependencies of various software libraries and ensures that projects that depend on libraries aren’t unexpectedly broken by new versions.

The format of semantic versioning is straightforward, expressed as X.Y.Z., where:

• X stands for a major version.
• Y stands for a minor version.
• Z stands for a patch version.

The rules of semantic versioning

1. Major version X: Increment the major version when you make incompatible API changes. This indicates that the new version may not be backwards compatible with previous versions.
2. Minor version Y: Increment the minor version when you add functionality in a backwards-compatible manner. This allows implementations to add features without disrupting existing usage.
3. Patch version Z: Increment the patch version when you make backwards-compatible bug fixes. This is primarily for making fixes that do not affect the software’s functionality.

Additional labels for pre-release and build metadata

• Pre-release versions can be denoted by appending a hyphen and a series of dot-separated identifiers immediately following the patch version. For example, 3.0.0-alpha.1.
• Build metadata can be included by appending a plus sign and a series of dot-separated identifiers immediately following the patch or pre-release version. For example, 3.0.0+20130313144700.

Benefits of using semantic versioning

Predictability: Developers can update dependencies, knowing they will not inadvertently break their software. Changes in major versions indicate breaking changes, minor versions indicate new features, and patches are just fixes.

Transparency: Changes in version numbers communicate the nature of changes in the software. This transparency builds trust and facilitates easier maintenance and upgrading of software.

Streamlined dependency management: Dependency management tools can automatically manage versions based on the semantic versioning specifications. This reduces the overhead of manual oversight in many development workflows.

Implementing semantic versioning in your project

Starting a new project

When you begin a new project, start with version 0.1.0. The initial development phase is typically a time when many changes might be made, and the software is not yet stable.

Here we have set the Major version to 0 as we would generally consider version 1 to be our initial release version.

Moving to production

Once your software is stable and ready for production, increment to version 1.0.0. This marks the public API’s stability and is a signal to users that the software is considered production-ready.

Version rules

• Increment the patch version for critical bug fixes and minor issues that do not affect the software’s operation.
• When adding new features that do not break existing functionality, bump the minor version.
• Make a major version increment when changes are breaking or remove previous functionalities.

Communicating changes

Maintain a change log to accompany your versioned software. This document should provide a clear history of the project, stating what changes were made with each version increment.

Fun fact

Python uses semantic versioning numbers, but it does not follow the strict rules of semantic versioning. While the version numbers might increase in a way that suggests adherence to SemVer, the changes between versions do not always align perfectly with the expected nature of these increments according to SemVer rules.

Final thoughts

Semantic versioning is not just a set of rules but a communication tool that helps developers maintain their software ecosystems efficiently. By adopting SemVer, you ensure that your project can grow and evolve while maintaining compatibility and trust with users and developers alike. Whether you’re maintaining a small library or a large enterprise system, proper versioning is key to a sustainable software development lifecycle.