5 Best Ways to Check Old and New Version Numbering Correctness in Python

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πŸ’‘ Problem Formulation: Ensuring that version numbering follows a consistent and logical pattern is crucial for software management and release control. Developers need to verify if a new version number is correctly incremented from the old one. For instance, the input could be the old version “1.2.3” and the new version “1.2.4”, and the desired output is a confirmation that the versioning is correct.

Method 1: Using the packaging.version module

This method leverages the parse function from the packaging.version module, part of the packaging library, which is a set of libraries and utilities for version handling. The function compares two version strings according to PEP 440 – a standard for version identification – ensuring that semantic versioning rules are followed.

Here’s an example:

from packaging import version

def are_versions_correct(old, new):
    return version.parse(old) < version.parse(new)

print(are_versions_correct("1.2.3", "1.2.4"))

Output:

True

This tiny function are_versions_correct() takes two string arguments: old and new, representing the old and new version numbers respectively. It uses the version.parse() function to convert these version strings into Version objects, which can then be directly compared to determine if the version increment is correct.

Method 2: Using LooseVersion and StrictVersion from distutils

Within Python’s distutils.version module, there are two classes – LooseVersion and StrictVersion. The former allows for a loose interpretation of version numbers, while the latter demands strict adherence to the format (major.minor[.patch][sub]).

Here’s an example:

from distutils.version import LooseVersion

def are_versions_correct(old, new):
    return LooseVersion(old) < LooseVersion(new)

print(are_versions_correct("1.2.3", "1.2.4"))

Output:

True

In this example, the are_versions_correct() function makes comparisons between version numbers by instantiating LooseVersion objects, which are then compared using standard comparison operators. The comparative evaluation confirms if the new version is indeed an increment.

Method 3: Manual String Splitting and Comparison

A straightforward approach can be to split the version strings manually, convert each component to an integer and then compare these integers in sequence. This method does not rely on external libraries and operates at the fundamental string and integer comparison level.

Here’s an example:

def are_versions_correct(old, new):
    old_nums = list(map(int, old.split('.')))
    new_nums = list(map(int, new.split('.')))
    return old_nums < new_nums

print(are_versions_correct("1.2.3", "1.2.4"))

Output:

True

The are_versions_correct() function splits each version by periods and then maps each substring into an integer to create a list of integers. Direct integer comparison ensures that the version increment is correct. It is crucial, however, to ensure that each version string is formatted correctly.

Method 4: Using a Custom Regular Expression

This method involves crafting a custom regular expression to match version numbers and extract their numerical components. With captured groups, these components can then be compared. This method is highly flexible and can accommodate bespoke versioning schemes.

Here’s an example:

import re

def are_versions_correct(old, new):
    pattern = re.compile(r'(\d+)\.(\d+)\.(\d+)')
    old_match = pattern.match(old)
    new_match = pattern.match(new)
    if old_match and new_match:
        return tuple(map(int, old_match.groups())) < tuple(map(int, new_match.groups()))
    return False

print(are_versions_correct("1.2.3", "1.2.4"))

Output:

True

In the function are_versions_correct(), the regular expression pattern is compiled, and then both old and new versions are matched against it. The groups() method extracts the version components, which are converted to integers and compared as tuples, providing the validation of version correctness.

Bonus One-Liner Method 5: Using Comparison within a Lambda

For a quick-and-dirty one-liner solution, a lambda function can encapsulate the whole process of splitting, converting, and comparing the version strings.

Here’s an example:

are_versions_correct = lambda old, new: list(map(int, old.split('.'))) < list(map(int, new.split('.')))

print(are_versions_correct("1.2.3", "1.2.4"))

Output:

True

The lambda function are_versions_correct uses the split and map techniques described in Method 3, but condensed into a single, albeit less readable, line of code. It can be useful for simple scripts where import overheads are undesirable.

Summary/Discussion

  • Method 1: packaging.version. Leverages a third-party library for robust, standards-compliant version comparison. Requires packaging library. Comprehensive but adds a dependency.
  • Method 2: distutils.version. Utilizes Python’s in-built modules for version comparison. While StrictVersion is stringent, LooseVersion allows flexibility. May not suit all version schemes.
  • Method 3: Manual String Splitting. Simple and straightforward, doesn’t depend on external libraries, but assumes correctly formatted version strings and may fail on non-standard versioning.
  • Method 4: Custom Regular Expression. Highly customizable, suitable for unique versioning systems. Requires understanding of regexes, and it may be overkill for simple cases.
  • Method 5: Lambda Comparison. Fast, compact, and no external dependencies. The downside is reduced readability and maintainability.