On Tue, 4/2/14, Nick Coghlan <ncoghlan@gmail.com> wrote:
It's a higher level of isolation than that offered by *not* installing pip into the virtual environments - the two approaches are *not* equivalent, and one is *not* clearly superior to the other, but rather there are pros and cons to both.
Obviously the two approaches aren't equivalent, or there wouldn't be anything to discuss. What you haven't yet done is answered my question about what the cons are of the not-in-venv approach in the practical "you can't do X, because of Y", sense. What *practical* problems are caused by a lower level of isolation exactly, which make the higher level of isolation necessary? ISTM the pip developers tried to implement -E because it was (independently of me) seen as a desirable feature, and Paul said as much, too. If it didn't work for pip, that could well be because of the specific implementation approach used, as I've said in my response to Carl. Rather than talk in abstractions like "higher levels of isolation", which have an implied sense of goodness, it would be helpful to spell out specific scenarios (in the X/Y sense I mentioned before) that illustrate that goodness versus the badness of other approaches. Regards, Vinay Sajip