From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Hinsen Subject: Re: installing python 2 and python 3 in the same profile Date: Mon, 12 Mar 2018 08:07:27 +0100 Message-ID: References: <87y3j4l3xj.fsf@mdc-berlin.de> <20180310083421.GA26219@thebird.nl> <87ina2uaum.fsf@elephly.net> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:58115) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1evHYQ-0004Mu-Hz for guix-devel@gnu.org; Mon, 12 Mar 2018 03:07:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1evHYL-00022D-Qf for guix-devel@gnu.org; Mon, 12 Mar 2018 03:07:30 -0400 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:58519) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1evHYL-00021b-Jv for guix-devel@gnu.org; Mon, 12 Mar 2018 03:07:25 -0400 In-Reply-To: <87ina2uaum.fsf@elephly.net> List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org Sender: "Guix-devel" To: Ricardo Wurmus , Pjotr Prins , Ricardo Wurmus , Guix-devel Ricardo Wurmus writes: > It is an unnecessary restriction to *prevent* users from installing > Python 2 and 3 interpreters into the same profile. Any errors we see I agree. But the current question is not if we should allow people to shoot themselves into the foot, but how much effort we should invest to make this possible. Pjotr Prins writes: >> It is an unnecessary restriction to *prevent* users from installing >> Python 2 and 3 interpreters into the same profile. Any errors we see >> with mixing 2 and 3 is due to a bug in Guix which is due to our use of >> PYTHONPATH. > > Alright, if you choose to use them as two different tools/languages. Which is what they are - the biggest mistake in the Python 2->3 transition was, in my opinion, to pretend they are the same language. It is possible to write programs that are valid in both languages but produce different results; this even happens regularly by mistake due to the change of division semantics. So by my definition, they are two similar but distinct languages. > Sure. Note that Python2 is quickly becoming obsolete. It is escalating > because packages are now dropping support. After 10 years of joy > mixing versions... I expect Python 2 to remain widely used for another 10 years after official support ends. Applications that have no security concerns can simply continue to build on the last official release of Python 2 and its library ecosystem. For applications with a high migration cost, it's still not worth the effort to port to Python 3. Konrad.