failed to install requirements on windows due to greenlet about flask-socketio-chat

[rayanth]

the error on greenlet is because you don't have a C++ compiler installed, or not configured, or not configured correctly that Python can find it.

You're semi-correct on requirements, but I argue against what you're trying to advocate.

Flask is a requirement of Flask-WTF, therefor installing Flask-WTF will install Flask implicitly. Likewise, Jinja is a requirement of Flask, so installing Flask (via Flask-WTF) will install Jinja implicitly... however, the requirements.txt file is very rarely manually created or edited - it's created via pip freeze > requirements.txt which will add every package from the virtual environment to the requirements.txt file. If it were then manually edited, and a new package added later, and the requirements.txt updated with a pip freeze, then the creator has to go back in and manually edit it again... for a small project that may not sound like a big deal, but for a large project, it's a nightmare.

Removing requirements because they are implied as dependencies of other requirements is a good way to have a big problem down the road when a dependency changes. Besides, as the Zen of Python says: Explicit is better than implicit.

[miguelgrinberg]

A failure when installing greenlet usually means that the greenlet package does not have a wheel package for the version of Python and/or operating system. I have seen this error recently when using Python 3.12, so the interim solution is to use Python 3.11, which installs greenlet from a wheel. Eventually the greenlet team will push wheels for 3.12 and everything will be good again.