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Python 3 virtualenvs

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  Python 3 virtualenvs real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) - 2015-11-28 00:37 +0000
    Re: Python 3 virtualenvs Laura Creighton <lac@openend.se> - 2015-11-28 02:09 +0100
      Re: Python 3 virtualenvs real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) - 2015-11-28 01:35 +0000
    Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs) Ben Finney <ben+python@benfinney.id.au> - 2015-11-28 12:42 +1100
    Re: Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs) Laura Creighton <lac@openend.se> - 2015-11-28 03:23 +0100
    Re: Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs) INADA Naoki <songofacandy@gmail.com> - 2015-11-28 16:17 +0900
    Re: Python 3 virtualenvs Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-11-28 13:29 +0000
      Re: Python 3 virtualenvs real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) - 2015-11-28 19:37 +0000
        Re: Python 3 virtualenvs Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-11-28 21:48 +0000
          Re: Python 3 virtualenvs Lele Gaifax <lele@metapensiero.it> - 2015-11-29 13:19 +0100
          Re: Python 3 virtualenvs Laura Creighton <lac@openend.se> - 2015-11-29 13:27 +0100
            Re: Python 3 virtualenvs Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-11-29 13:23 +0000
              Re: Python 3 virtualenvs Laura Creighton <lac@openend.se> - 2015-11-29 15:12 +0100
              Re: Python 3 virtualenvs Carl Meyer <carl@oddbird.net> - 2015-11-30 09:32 -0700
              Re: Python 3 virtualenvs Laura Creighton <lac@openend.se> - 2015-11-30 18:20 +0100
              Re: Python 3 virtualenvs Carl Meyer <carl@oddbird.net> - 2015-11-30 10:28 -0700
                Re: Python 3 virtualenvs Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-11-30 17:30 +0000
              Re: Python 3 virtualenvs Laura Creighton <lac@openend.se> - 2015-11-30 18:46 +0100

#99646 — Python 3 virtualenvs

I have a new installation of Debian Jessie, with Python 2.7 and 3.4
installed.

I want to use Python 3.4 by default for most things, so I want
virtualenv to create Python 3.4 virtualenvs unless I ask it to
otherwise.

It turns out that this seems to be inordinately complex.

The best solution I have come up with is to alias virtualenv to
'virtualenv -p python3.5', which seems really ugly and clunky.

Then I discover things like
<http://askubuntu.com/questions/603935/pyvenv-vs-venv-vs-python-virtualenv-vs-virtualenv-and-python-3>
and realise it's not just me, it really is a nasty mess and nobody seems
to understand what's going on.

Daniele

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#99647

In a message of Sat, 28 Nov 2015 00:37:21 +0000, D.M. Procida writes:
>I have a new installation of Debian Jessie, with Python 2.7 and 3.4
>installed.
>
>I want to use Python 3.4 by default for most things, so I want
>virtualenv to create Python 3.4 virtualenvs unless I ask it to
>otherwise.
>
>It turns out that this seems to be inordinately complex.
>
>The best solution I have come up with is to alias virtualenv to
>'virtualenv -p python3.5', which seems really ugly and clunky.

This will get you python3.5 which I infinitely prefer over 3.4. 
But you said you wanted to use 3.4 ...

>Then I discover things like
><http://askubuntu.com/questions/603935/pyvenv-vs-venv-vs-python-virtualenv-vs-virtualenv-and-python-3>
>and realise it's not just me, it really is a nasty mess and nobody seems
>to understand what's going on.
>
>Daniele

What I found out.
https://bugs.python.org/issue25151
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732703
https://bugs.python.org/issue25152
https://bugs.python.org/issue25154

pyenv is going away.  use python -m venv instead, if you want a 
venv.  You will never (unless somebody does a backport, which seems
very unlikley) be able to get a venv with 2.7.

I've long ago aliased virtualenv to v, so things aren't as clunky
for me.

Laura

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#99648

Laura Creighton <lac@openend.se> wrote:

> In a message of Sat, 28 Nov 2015 00:37:21 +0000, D.M. Procida writes:
> >I have a new installation of Debian Jessie, with Python 2.7 and 3.4
> >installed.
> >
> >I want to use Python 3.4 by default for most things, so I want
> >virtualenv to create Python 3.4 virtualenvs unless I ask it to
> >otherwise.
> >
> >It turns out that this seems to be inordinately complex.
> >
> >The best solution I have come up with is to alias virtualenv to
> >'virtualenv -p python3.5', which seems really ugly and clunky.
> 
> This will get you python3.5 which I infinitely prefer over 3.4. 
> But you said you wanted to use 3.4 ...

Typo!

> >Then I discover things like
> ><http://askubuntu.com/questions/603935/pyvenv-vs-venv-vs-python-virtualen
> >v-vs-virtualenv-and-python-3> and realise it's not just me, it really is
> >a nasty mess and nobody seems to understand what's going on.

> What I found out.
> https://bugs.python.org/issue25151
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732703
> https://bugs.python.org/issue25152
> https://bugs.python.org/issue25154

Good lord.

> I've long ago aliased virtualenv to v, so things aren't as clunky
> for me.

I'll stick with virtualenv as an alias to virtualenv -p python3.5.
 
Thanks,

Daniele

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#99649 — Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs)

Laura Creighton <lac@openend.se> writes:

> […] python3.5 which I infinitely prefer over 3.4. 

That's strong language :-)

Laura – and anyone else – what in your opinion are the best improvements
brought by Python 3.5 (over Python 3.4)?

-- 
 \     “DRM doesn't inconvenience [lawbreakers] — indeed, over time it |
  `\     trains law-abiding users to become [lawbreakers] out of sheer |
_o__)                        frustration.” —Charles Stross, 2010-05-09 |
Ben Finney

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#99650 — Re: Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs)

In a message of Sat, 28 Nov 2015 12:42:30 +1100, Ben Finney writes:
>Laura Creighton <lac@openend.se> writes:
>
>> […] python3.5 which I infinitely prefer over 3.4. 
>
>That's strong language :-)
>
>Laura – and anyone else – what in your opinion are the best improvements
>brought by Python 3.5 (over Python 3.4)?

The interactive console started working again.
https://bugs.python.org/issue23441

Laura

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#99654 — Re: Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs)

OrderedDict is now faster and efficient.

On Sat, Nov 28, 2015 at 10:42 AM, Ben Finney <ben+python@benfinney.id.au>
wrote:

> Laura Creighton <lac@openend.se> writes:
>
> > […] python3.5 which I infinitely prefer over 3.4.
>
> That's strong language :-)
>
> Laura – and anyone else – what in your opinion are the best improvements
> brought by Python 3.5 (over Python 3.4)?
>
> --
>  \     “DRM doesn't inconvenience [lawbreakers] — indeed, over time it |
>   `\     trains law-abiding users to become [lawbreakers] out of sheer |
> _o__)                        frustration.” —Charles Stross, 2010-05-09 |
> Ben Finney
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
INADA Naoki  <songofacandy@gmail.com>

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#99662

On 2015-11-28, D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
> I have a new installation of Debian Jessie, with Python 2.7 and 3.4
> installed.
>
> I want to use Python 3.4 by default for most things, so I want
> virtualenv to create Python 3.4 virtualenvs unless I ask it to
> otherwise.
>
> It turns out that this seems to be inordinately complex.

sudo apt-get remove python-virtualenv
sudo apt-get install python3-virtualenv

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#99674

Jon Ribbens <jon+usenet@unequivocal.co.uk> wrote:

> On 2015-11-28, D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk>
wrote:
> > I have a new installation of Debian Jessie, with Python 2.7 and 3.4
> > installed.
> >
> > I want to use Python 3.4 by default for most things, so I want
> > virtualenv to create Python 3.4 virtualenvs unless I ask it to
> > otherwise.
> >
> > It turns out that this seems to be inordinately complex.
> 
> sudo apt-get remove python-virtualenv
> sudo apt-get install python3-virtualenv

Yup, I did try installing python3-virtualenv, but it didn't appear
actually do do anything. It didn't provide me with a virtualenv command,
that's for sure.

And pages such as https://packages.debian.org/jessie/python3-virtualenv
are not exactly informative.

Is something else required?

Daniele 

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#99677

On 2015-11-28, D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
> Jon Ribbens <jon+usenet@unequivocal.co.uk> wrote:
>
>> On 2015-11-28, D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk>
> wrote:
>> > I have a new installation of Debian Jessie, with Python 2.7 and 3.4
>> > installed.
>> >
>> > I want to use Python 3.4 by default for most things, so I want
>> > virtualenv to create Python 3.4 virtualenvs unless I ask it to
>> > otherwise.
>> >
>> > It turns out that this seems to be inordinately complex.
>> 
>> sudo apt-get remove python-virtualenv
>> sudo apt-get install python3-virtualenv
>
> Yup, I did try installing python3-virtualenv, but it didn't appear
> actually do do anything. It didn't provide me with a virtualenv command,
> that's for sure.
>
> And pages such as https://packages.debian.org/jessie/python3-virtualenv
> are not exactly informative.
>
> Is something else required?

Hmm. Well basically the answer to your question is that you want
virtualenv to be installed by Python 3, then it will default to using
it. Debian's package management is mysterious and apparently bizarre
and frankly in respect to Python, not very good. So perhaps the best
thing to do is simply ignore it and install virtualenv yourself with:

  sudo apt-get install python3-pip
  sudo pip3 install virtualenv

... although you might want to install pip manually too.

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#99690

Jon Ribbens <jon+usenet@unequivocal.co.uk> writes:

> On 2015-11-28, D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
>>
>> Is something else required?
>
> Debian's package management is mysterious and apparently bizarre
> and frankly in respect to Python, not very good.

I do not agree with you on the quality of Python support on Debian systems,
but I think Daniele is missing the package "pythonX.Y-venv": they install the
needed stuff, and in particular /usr/bin/pyvenv-X-Y.

ciao, lele.
-- 
nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri
real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia.
lele@metapensiero.it  |                 -- Fortunato Depero, 1929.

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#99691

In a message of Sun, 29 Nov 2015 13:19:46 +0100, Lele Gaifax writes:
>Jon Ribbens <jon+usenet@unequivocal.co.uk> writes:
>
>> On 2015-11-28, D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
>>>
>>> Is something else required?
>>
>> Debian's package management is mysterious and apparently bizarre
>> and frankly in respect to Python, not very good.
>
>I do not agree with you on the quality of Python support on Debian systems,
>but I think Daniele is missing the package "pythonX.Y-venv": they install the
>needed stuff, and in particular /usr/bin/pyvenv-X-Y.
>
>ciao, lele.

No, Pyvenv is precisely what Daniele can not use.
The problem is that venv does not come with a big sign saying

ONLY FOR PYTHON 3.x
ABSOLUTELY DOES NOT WORK FOR BUILDING 2.7 VIRTUALENVS
USE virtualenv INSTEAD for Python 2.7

----

which means you can waste a whole lot of time finding this out
the hard way.

Laura

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#99692

On 2015-11-29, Laura Creighton <lac@openend.se> wrote:
> In a message of Sun, 29 Nov 2015 13:19:46 +0100, Lele Gaifax writes:
>>Jon Ribbens <jon+usenet@unequivocal.co.uk> writes:
> No, Pyvenv is precisely what Daniele can not use.
> The problem is that venv does not come with a big sign saying
>
> ONLY FOR PYTHON 3.x
> ABSOLUTELY DOES NOT WORK FOR BUILDING 2.7 VIRTUALENVS
> USE virtualenv INSTEAD for Python 2.7
>
> ----
>
> which means you can waste a whole lot of time finding this out
> the hard way.

More specifically, "only for Python >= 3.4", because before that
it does not install pip, which makes it fairly useless.

In my experience the best thing to do is ignore pyvenv and ignore
Debian's package management for anything other than installing
the Python interpreter itself. Install pip by hand, then use that
to install virtualenv, then just use those to create virtualenvs
to run your stuff.

I don't know if, in future, pyvenv will be the way to go and
virtualenv will be deprecated, but either way we do not appear
to be there yet.

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#99694

In a message of Sun, 29 Nov 2015 13:23:19 +0000, Jon Ribbens writes:
>I don't know if, in future, pyvenv will be the way to go and
>virtualenv will be deprecated, but either way we do not appear
>to be there yet.

pyenv is going away.  python -m venv is the preferred way to get a venv

https://bugs.python.org/issue25154

Of course if you try it, you may get:

  Error: Command '['<directory>/bin/python3.4', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1

which turns out to mean:

Your Python isn't configured with ensure-pip!

.....

Right now, I personally don't know why there is a venv at all.  Despite
the similarity of names, it doesn't seem to be about doing what virtualenv
does.  I think it is only meant to be used by people who want to install
packages but not site-wide, but I am not sure about that.  I don't think
there are any plans to give venv the functionality of virtualenv, so
presumably there are people who like it just fine the way it is now.
They must have very different needs than I do.

Laura

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#99742

[Multipart message — attachments visible in raw view] — view raw

Hi Laura,

On 11/29/2015 07:12 AM, Laura Creighton wrote:
> pyenv is going away.  python -m venv is the preferred way to get a venv
> 
> https://bugs.python.org/issue25154
> 
> Of course if you try it, you may get:
> 
>   Error: Command '['<directory>/bin/python3.4', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1
> 
> which turns out to mean:
> 
> Your Python isn't configured with ensure-pip!

AFAIK "isn't configured with ensurepip" is a thing which is only done to
Python by some downstream distributors (e.g. Linux packagers). If they
remove ensurepip, it should be their responsibility to also fix the venv
module accordingly (at least enough to provide a useful error message).
So I believe that's a bug that should be filed against whoever is
distributing the Python you're using.

> Right now, I personally don't know why there is a venv at all.

Because virtualenv is an ugly hack which is difficult to maintain (I
should know, I used to maintain it). In order to work at all, virtualenv
maintains its own patched copy of several stdlib modules (based
originally on Python 2.4(?) and modified since then) and uses them
instead of the version distributed with whatever version of Python you
are using. Some other stdlib modules it monkeypatches. As you might
expect, this regularly causes problems when new Python versions are
released, requiring even more hacks piled atop the previous ones.

It's a real testament to the dedication of the current virtualenv
maintainers (thank you, PyPA!) that it even works at all.

The built-in venv module in Python 3.3+ fixes that by building a minimal
level of support for virtual environments directly into the Python
interpreter and stdlib, removing the need for (monkey)patching. Of
course that interpreter support isn't available in Pythons prior to 3.3,
which is why virtualenv remains much more popular today.

(Also, the first version of venv in Python 3.3 didn't automatically
install pip into the envs, which made them less useful, because at that
point pip was a purely third-party project. That's been fixed with
ensurepip in Python 3.4+).

I very much hope that some day in the future, when all new Python
projects are in Python 3, almost everyone will use venv, and virtualenv
will be relevant only to those maintaining legacy Python 2 projects.

There has been some work towards writing a transitional version of
virtualenv that looks the same to users, but (under the hood) uses the
old code only for 2.x and uses venv for Python 3.

>  Despite
> the similarity of names, it doesn't seem to be about doing what virtualenv
> does.

I don't know what you mean by this. Venv is intended to do _exactly_
what virtualenv does, only better. Unless by "what virtualenv does" you
mean "also support Python 2."

> I think it is only meant to be used by people who want to install
> packages but not site-wide, but I am not sure about that.

I don't know what you mean by this either. Isn't the ability to "install
packages but not site-wide" precisely what virtualenv (and venv) give you?

> I don't think
> there are any plans to give venv the functionality of virtualenv,

What functionality do you mean?

> so
> presumably there are people who like it just fine the way it is now.
> They must have very different needs than I do.

I don't know, since you never said what it is about venv that doesn't
meet your needs :-)

Carl

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#99747

In a message of Mon, 30 Nov 2015 09:32:27 -0700, Carl Meyer writes:
>Hi Laura,

>I don't know what you mean by this. Venv is intended to do _exactly_
>what virtualenv does, only better. Unless by "what virtualenv does" you
>mean "also support Python 2."

That is exactly what I mean.

>> I think it is only meant to be used by people who want to install
>> packages but not site-wide, but I am not sure about that.
>
>I don't know what you mean by this either. Isn't the ability to "install
>packages but not site-wide" precisely what virtualenv (and venv) give you?

I rarely use it for that.  What I nearly always want is different
python interpreters.  CPython, PyPy, Jython for anything from 2.6 to
3.6.

Laura

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#99748

[Multipart message — attachments visible in raw view] — view raw

On 11/30/2015 10:20 AM, Laura Creighton wrote:
> In a message of Mon, 30 Nov 2015 09:32:27 -0700, Carl Meyer writes:
>>> I think it is only meant to be used by people who want to install
>>> packages but not site-wide, but I am not sure about that.
>>
>> I don't know what you mean by this either. Isn't the ability to "install
>> packages but not site-wide" precisely what virtualenv (and venv) give you?
> 
> I rarely use it for that.  What I nearly always want is different
> python interpreters.  CPython, PyPy, Jython for anything from 2.6 to
> 3.6.

If you just want the variety of interpreters, virtualenv doesn't give
you that -- you have to already have a given interpreter installed
system-wide for virtualenv to be able to use it. What virtualenv gives
you is isolated environments for package installations (which can use
any interpreter you have installed).

Venv does the same (and won't have any trouble with PyPy or Jython
either, once they reach Python 3.3 compatibility).

So I agree that for now you should be sticking with virtualenv (I use it
too), but I hope you'll take another look at venv a few years down the
road, if you find yourself in a situation where all the interpreters you
need are 3.3+.

(Or maybe virtualenv will make the transition sooner, and you'll start
using venv under the hood for 3.3+ without even realizing it.)

Carl

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#99750

On 2015-11-30, Carl Meyer <carl@oddbird.net> wrote:
> (Or maybe virtualenv will make the transition sooner, and you'll start
> using venv under the hood for 3.3+ without even realizing it.)

It does sound like that would be the ideal solution, and presumably
can't be very hard if venv is supposed to do exactly what virtualenv
does anyway - virtualenv just needs to say "if python >= 3.4 then
call venv".

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#99754

In a message of Mon, 30 Nov 2015 10:28:46 -0700, Carl Meyer writes:

>So I agree that for now you should be sticking with virtualenv (I use it
>too), but I hope you'll take another look at venv a few years down the
>road, if you find yourself in a situation where all the interpreters you
>need are 3.3+.

I will, but these days I am playing with fades, which I only discovered
a week ago, when Facundo made an announcment.
https://pypi.python.org/pypi/fades/3

And it looks like this will make my life a whole lot easier.

Laura

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