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A library implementing the 'SemVer' scheme.

Project description


This small python library provides a few tools to handle SemVer in Python. It follows strictly the 2.0.0 version of the SemVer scheme. Latest Version Supported Python versions Wheel status License

Getting started

Install the package from PyPI, using pip:

pip install semantic-version

Or from GitHub:

$ git clone git://

Import it in your code:

import semantic_version

This module provides classes to handle semantic versions:

  • Version represents a version number (0.1.1-alpha+build.2012-05-15)

  • BaseSpec-derived classes represent requirement specifications (>=0.1.1,<0.3.0):

    • SimpleSpec describes a natural description syntax

    • NpmSpec is used for NPM-style range descriptions.


Defining a Version is quite simple:

>>> import semantic_version
>>> v = semantic_version.Version('0.1.1')
>>> v.major
>>> v.minor
>>> v.patch
>>> v.prerelease
>>> list(v)
[0, 1, 1, [], []]

If the provided version string is invalid, a ValueError will be raised:

>>> semantic_version.Version('0.1')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/rbarrois/dev/semantic_version/src/semantic_version/", line 64, in __init__
    major, minor, patch, prerelease, build = self.parse(version_string, partial)
  File "/Users/rbarrois/dev/semantic_version/src/semantic_version/", line 86, in parse
    raise ValueError('Invalid version string: %r' % version_string)
ValueError: Invalid version string: '0.1'

One may also create a Version with named components:

>>> semantic_version.Version(major=0, minor=1, patch=2)

In that case, major, minor and patch are mandatory, and must be integers. prerelease and build, if provided, must be tuples of strings:

>>> semantic_version.Version(major=0, minor=1, patch=2, prerelease=('alpha', '2'))

Some user-supplied input might not match the semantic version scheme. For such cases, the Version.coerce method will try to convert any version-like string into a valid semver version:

>>> Version.coerce('0')
>>> Version.coerce('')
>>> Version.coerce('0.1.2a3')

Working with versions

Obviously, versions can be compared:

>>> semantic_version.Version('0.1.1') < semantic_version.Version('0.1.2')
>>> semantic_version.Version('0.1.1') > semantic_version.Version('0.1.1-alpha')
>>> semantic_version.Version('0.1.1') <= semantic_version.Version('0.1.1-alpha')

You can also get a new version that represents a bump in one of the version levels:

>>> v = semantic_version.Version('0.1.1+build')
>>> new_v = v.next_major()
>>> str(new_v)
>>> v = semantic_version.Version('1.1.1+build')
>>> new_v = v.next_minor()
>>> str(new_v)
>>> v = semantic_version.Version('1.1.1+build')
>>> new_v = v.next_patch()
>>> str(new_v)

Requirement specification

python-semanticversion provides a couple of ways to describe a range of accepted versions:

  • The SimpleSpec class provides a simple, easily understood scheme – somewhat inspired from PyPI range notations;

  • The NpmSpec class supports the whole NPM range specification scheme:

    >>> Version('0.1.2') in NpmSpec('0.1.0-alpha.2 .. 0.2.4')
    >>> Version('0.1.2') in NpmSpec('>=0.1.1 <0.1.3 || 2.x')
    >>> Version('2.3.4') in NpmSpec('>=0.1.1 <0.1.3 || 2.x')

The SimpleSpec scheme

Basic usage is simply a comparator and a base version:

>>> s = SimpleSpec('>=0.1.1')  # At least 0.1.1
>>> s.match(Version('0.1.1'))
>>> s.match(Version('0.1.1-alpha1'))  # pre-release doesn't satisfy version spec
>>> s.match(Version('0.1.0'))

Combining specifications can be expressed as follows:

>>> SimpleSpec('>=0.1.1,<0.3.0')

Simpler test syntax is also available using the in keyword:

>>> s = SimpleSpec('==0.1.1')
>>> Version('0.1.1+git7ccc72') in s  # build variants are equivalent to full versions
>>> Version('0.1.1-alpha1') in s     # pre-release variants don't match the full version.
>>> Version('0.1.2') in s

Refer to the full documentation at for more details on the SimpleSpec scheme.

Using a specification

The SimpleSpec.filter method filters an iterable of Version:

>>> s = SimpleSpec('>=0.1.0,<0.4.0')
>>> versions = (Version('0.%d.0' % i) for i in range(6))
>>> for v in s.filter(versions):
...     print v

It is also possible to select the ‘best’ version from such iterables:

>>> s = SimpleSpec('>=0.1.0,<0.4.0')
>>> versions = (Version('0.%d.0' % i) for i in range(6))


In order to contribute to the source code:

When submitting patches or pull requests, you should respect the following rules:

  • Coding conventions are based on PEP 8

  • The whole test suite must pass after adding the changes

  • The test coverage for a new feature must be 100%

  • New features and methods should be documented in the reference section and included in the changelog

  • Include your name in the contributors section

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