Version

Python Semantic Versioning

A lightweight Python library for parsing, comparing, and managing Semantic Version strings that gives you a single, well-tested Version class that handles the full SemVer specification correctly — including the subtleties of pre-release and build metadata ordering — with no external dependencies.

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Installation

Install python-versioning using pip:

pip install python-versioning

Requirements: Python 3.7+

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Features

• Single Class — A single Version class that handles semantic versioning.
• Full SemVer Support — Supports Major, minor, patch, pre-release and build metadata
• Comparable — All six comparison operators are built in (<, <=, >, >=, ==, !=)
• Track Multiple Versions — Track mulitple versions in a single instance.

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Usage

First import:

from version import Version

Major, Minor, Patch

Define Version class with SemVer 1.4.2:

from version import Version

v = Version('1.4.2')
print(v.major)        # 1
print(v.minor)        # 4
print(v.patch)        # 2
print(v.version)      # '1.4.2'

Pre-release and build metadata

Define Version class with SemVer 2.0.0-alpha.1+build.42:

from version import Version

v = Version('2.0.0-alpha.1+build.42')
print(v.major)        # 2
print(v.minor)        # 0
print(v.patch)        # 0
print(v.pre_release)  # ['alpha', 1]
print(v.build)        # ['build', 42]
print(v.version)      # '2.0.0-alpha.1+build.42'

Compare versions

All six comparison operators are supported (<, <=, >, >=, ==, !=):

Version('1.0.0') < Version('2.0.0')       # True
Version('1.0.0-alpha') < Version('1.0.0') # True  (pre-release < release)
Version('1.0.0') == Version('1.0.0')      # True
Version('2.0.0') > Version('1.9.9')       # True

Comparing against a non-Version raises a TypeError:

Version('1.0.0') < '1.0.1'  # raises TypeError

Track Multiple Versions

Initialize with a list and the object is automatically set to the latest valid version:

v = Version(['1.0.0', '3.2.1', '2.0.0-beta', 'not-a-version'])
print(v)  # '3.2.1'  — invalid entries are silently skipped

Add additional versions over time. If a new version is added, it becomes latest version:

v = Version('1.0.0')
print(v.version)      # '1.0.0'

v.add('2.0.0')
print(v.version)      # '2.0.0'

v.add('1.5.0')
print(v.version)      # '2.0.0'

v.add('3.0.1')
print(v.version)      # '3.0.1'

Duplicates are ignored and invalid strings raise VersionError:

v.add('1.0.0')        # no-op, already tracked
v.add('bad-version')  # raises VersionError

Remove versions:

v = Version('1.0.0')
v.add('2.0.0')
v.remove('1.0.0')

Removing the only version raises VersionError:

v = Version('1.0.0')
v.remove('1.0.0') # Cannot remove this version

Removing the latest version reverts to the next latest:

v = Version('1.0.0')
v.add('2.0.0')
v.add('2.1.0')
print(v.version)      # '2.1.0'

v.remove('2.1.0') 
print(v.version)      # '2.0.0'

Get the latest tracked version

v = Version('1.0.0')
v.add('3.0.0')
v.add('2.0.0')
print(v.latest)  # '3.0.0'

Inspect all tracked versions

v = Version(['1.0.0', '2.0.0', '3.0.0'])
for version in v.versions:
    print(version)
# 1.0.0
# 2.0.0
# 3.0.0

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Comparison Rules

This library follows the SemVer 2.0.0 specification exactly:

1. Major, minor, patch are compared numerically.
2. Pre-release versions have lower precedence than the release version (1.0.0-alpha < 1.0.0).
3. When both versions have a pre-release, identifiers are compared left to right:
   • Numeric identifiers are compared as integers.
   • Alphanumeric identifiers are compared lexically.
   • Numeric identifiers always have lower precedence than alphanumeric ones (1 < alpha).
   • A shorter pre-release has lower precedence than a longer one with the same prefix (alpha < alpha.1).
4. Build metadata follows the same ordering rules as pre-release, and a version with build metadata has lower precedence than one without.

The full canonical precedence order from the SemVer spec:

1.0.0-alpha
1.0.0-alpha.1
1.0.0-alpha.beta
1.0.0-beta
1.0.0-beta.2
1.0.0-beta.11
1.0.0-rc.1
1.0.0

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Error Handling

VersionError is raised for any invalid version string:

Version('')           # VersionError: invalid version ''
Version('v1.0.0')     # VersionError: invalid version 'v1.0.0'
Version('1.0')        # VersionError: invalid version '1.0'
Version([])           # VersionError: No versions provided in the list
Version(['bad'])      # VersionError: No valid versions found in the list

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API Reference

Version(version: str | list[str])

Creates a Version instance.

• If given a string, parses and validates it.
• If given a list, filters out invalid entries, raises if none remain, and sets the instance to the highest valid version.

Attribute / Property	Type	Description
major	int	Major version number
minor	int	Minor version number
patch	int	Patch version number
pre_release	list[int | str]	Parsed pre-release identifiers
build	list[int | str]	Parsed build metadata identifiers
version	str	String form of this version
versions	list[Version]	All tracked versions as Version objects
latest	Version	Highest version in the tracked list

Version.add(version: str) -> None

Adds a version string to the tracked list. No-op if already present. Raises VersionError if the string is invalid.

Version.remove(version: str) -> None

Removes a version string from the tracked list. Raises VersionError if attempt to remove only version.

VersionError

Subclass of Exception. Raised when a version string does not conform to the SemVer format.

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Run Tests

80/80 tests passed

python -m pytest tests/test.py -v