outdated 0.2.2

Description:

outdated 0.2.2

outdated

This is a mini-library which, given a package name and a version, checks if it's the latest version available on PyPI.
To install:
pip install outdated

Quickstart:
from outdated import warn_if_outdated

warn_if_outdated('my-package-name', '1.2.3')

This will:

Show a warning if the given version is not the latest. The warning includes the package name, the given version, and the latest version.
Perform the check in a background thread (so it doesn't delay anything)
Make at most one HTTP call (unless there is an HTTP error, in which case it will try 3 times) to the PyPI server for that specific package
Cache the result of the HTTP call on disk for 24 hours
Show a warning if any exception occurs during the check

This will not check what version is currently installed, it will only use the given version. Library authors must make sure that the version in their setup.py matches the version here.
The package name argument must be exactly the name used on PyPI, so that e.g. https://pypi.python.org/pypi/my-package-name is a valid URL.
Optional arguments:

background (default True): run the check in a separate thread. Set to False to run immediately.
raise_exceptions (default: False): if True, allow exceptions to bubble to the top. Otherwise, show a warning including the exception message. If background is True and this is True then this will result in a full traceback showing but the process continuing.

Lower level API
from outdated import check_outdated

is_outdated, latest_version = check_outdated('my-package-name', '1.2.3')

is_outdated is a boolean which is True if the given version is earlier than the latest version, which is the string latest_version.
Optional arguments:

repository_url (default https://pypi.python.org/pypi/%s/json): a % style format string to use a different repository PyPI repository URL, e.g. test.pypi.org or a private repository. The string is formatted with the package name.

This still makes the HTTP call with retries and caches the result on disk. It doesn't use a separate thread or emit any warnings (unless there is an exception specifically while using the cache, in which case the check will be done without the cache).
Additional configuration
To disable all warnings from this library, set the environment variable OUTDATED_IGNORE to any non-empty value.
To always raise exceptions instead of converting them to warnings (both in general in warn_if_outdated and more specifically when there's a caching problem) set the environment variable OUTDATED_RAISE_EXCEPTION=1.
The warnings are also categorised so that you can easily control them with standard warning filters. The classes are here and can be imported directly from the outdated module.
Performance
This library works by fetching a URL such as this - the time it takes to visit that link is essentially the speed of the library. This is much faster than the command pip list --outdated or any equivalent code.