On Windows, which is the only platform I can reasonably comment on, the killer issue is that the installer doesn't make the commands "python" and "pip" available by default. Just checking my PC, both go and rust (which I installed *ages* ago) do appear to, so they "just work". Java sort-of also works like that (the runtime is on PATH, but the compilers need to be added manually).
The biggest reason we don't add Python to PATH, as I understand it, is because we need to consider the implications of people having multiple versions of Python installed. As far as I know, no other language allows that. But equally, most beginners wouldn't actually *have* multiple versions installed. So maybe we should optimise for that case (only one version of Python installed). That would mean:
That seems reasonable. Especially since somebody with several versions install is more likely to know how to deal with system path issues than a total beginner installing python for the first time.
- Go back to adding Python to PATH. Because our installers don't say
"do you want to uninstall the old version", we should probably do a check for a "python" command on PATH in the installer, and if there is one, warn the user "You already have Python installed - if you are upgrading you should manually uninstall the old version first, otherwise your old installation will remain the default". We could get more complex at this point, but that depends on what capabilities we can include in the installer - I don't know how powerful the toolset is.
You don't even have to do that. We can detect it and prompt : "which python version do you want to be available by default ?", and then list command to run the alternative versions.
- Explicitly document that multiple Python interpreters on one
machine is considered "advanced", and users with that sort of setup should be prepared to manage PATH themselves. I'd put that as something like "It is possible to install multiple versions of Python at once, but if you do that, you should understand the implications - the average user should not need to do this"
We still have to deal with the fact that basically every Unix environment is "advanced" in the above sense (the python2/python3 split). I don't have a solution for that (other than "upgrade to Windows" ;-)).
Provide the "py" command on linux and mac. And make it the default recommended way in the documentation.
It doesn't completely solve the problem (as getting into and out of the environment is still platform specific), but it does mean that the ubiquitous online instructions to run "pip install package-name" and "python -m command" will actually work once people are inside their working environment.
That tooling is venv:
- it ensures you have "pip" on your PATH
- it ensures you have "python" on your PATH
- it ensures that you have the required permissions to install new packages
- it ensures that any commands you install from PyPI will be also on your PATH
When we choose not to use venv, then it becomes necessary to ensure each of those things individually for each potential system starting state
Currently, the reality is that people use virtualenv, not venv. All higher-level tools I'm aware of wrap virtualenv (to allow Python 2.7 support). Enhancing the capabilities of venv is fine, but promoting venv over virtualenv involves technical challenges across the whole toolset, not just documentation/education.
But agreed, once we get people into a virtual environment (of any form) the portability issues become significantly reduced. The main outstanding issue is managing multiple environments, which could be handled by having a special "default" environment that is the only one we'd expect beginners to use/need.
Well, not exactly. Do you do python -m venv, or py -x.x -m venv or pythonx -m venv ? Wait, it's not installed by default on debian.
And then virtualenv have their own issues:
- it's a contextual mode that you need to activate AND be aware of at all time - you need to config tooling to use it (IDE, builders, etc) - the location of virtualenv is very important - you should not commit it to git - you can't relocate it easily - install jupyter / mymy / flake8 outside a virtualenv and the command will still seems to work inside a virtualenv it's not installed in. With terrible consequences.
Virtualenvs are a hard tool to use for beginners.
A lot of people on this list have forgotten their early years it seems.
Also on Windows, the per-user bin directory isn't added to PATH even if you add the system Python to PATH in the installer.
That said, I think there is one improvement we could feasibly make, which would be to introduce the notion of a "default user environment" into `venv`, such that there was a single "python -m venv shell" command that:
- created a default user environment if it didn't already exist
- launched a subshell with that environment already activated
This wouldn't be a full environment manager like vex or pew - it would just be a way to bootstrap a single usable package management environment in a cross-platform way.
"How do I run venv?" is no easier to answer in a cross-platform way than "how do I run pip?" You still need to be able to run python/python3/py. About the only improvement is that there's no legacy of documentation and advice on the web saying "run venv" like there is for "run pip"...
Paul
Exactly.