[Python-ideas] Make py.exe default to Python 3

[Paul Moore]

On 16 March 2016 at 17:17, Chris Barker <chris.barker at noaa.gov> wrote:
> As in:
>
> If someone installs a version of python with defaults, they should then get
> that version when they type "python" (or maybe "py") at the command line.
>
> If they want something other than the last one they installed, then they'll
> have to mess with PATH or other configuration...

In theory, this makes sense to me. What it needs is someone to
champion it. And address the inevitable questions/objections. The ones
I immediately thought of were:

1. What if I want to install a version *not* for day to day use but
just for testing (i.e., there needs to be an easily accessible "leave
PATH alone" option).
2. How does this interact with uninstalls and upgrades? If I install
3.7, then 3.8 then uninstall 3.7, then install 3.6, then upgrade 3.8
to 3.8.1, what's left on PATH? (The answer I *want* is 3.8.1. That may
well be a nightmare to implement). How does the above change if
somewhere in the middle of that process I manually change PATH (in
which case I may well *not* want 3.8.1 as the end result!)

It's easy enough to dismiss point (2) as "well, you know what you're
doing", but I have experience of people doing a series of installs
like this, getting confused with PATH and doing a google search to
find out how to "fix" it. So it is a genuine situation a non-expert
user could find themselves in.

> After all, what do people expect when they have MSWord version X, and then install MSWord version X+1

But nobody *ever* runs multiple versions of MS Word. Whereas there are
genuine reasons for people (and not just experts, although admittedly
not complete beginners) to run multiple versions of Python. The MS
Word argument implies that the Python installer should automatically
and silently uninstall any older versions of Python present on the
user's machine.

Paul