[TIP] Why does tox use "pip install --pre" by default?

Carl Meyer carl at oddbird.net
Mon Sep 29 10:05:24 PDT 2014

On 09/29/2014 05:41 AM, Ned Batchelder wrote:
> On 9/29/14 3:32 AM, holger krekel wrote:
>> Even today i sometimes i forget to tell people to use "pip install --pre"
>> instead of just "pip install" to test out release files of mine.

They shouldn't need --pre at all if they are specifying precisely which
pre-release version they want to test, which I would consider preferable

>  And I
>> guarantee that changing tox' current default for "install_command" will
>> break things for some people.  Question is only how many and if the
>> consistency with pip is worth it in the long run.
> I agree this is the right approach: first decide how it should behave,
> then assess what might break.

It seems to me that (apart from backwards-compatibility concerns) it
would be better for tox to follow pip's default behavior by default. I
think it's fairly clear that a new tox user, absent specific information
from tox's docs, would assume that specifying a dependency on "coverage"
in their tox.ini will install the same version of coverage that is
installed by "pip install coverage".

I am not in a good position to evaluate the likely back-compat effects,
since I don't ever use tox in a way that relies on --pre (if I want to
test against a pre-release version of a dependency, I specify the
precise pre-release I want to test against).

I suppose it would be possible (though probably ugly) to implement this
change with a deprecation-warning cycle.


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