3.4rc2 and pip on windows

Ned Deily nad at acm.org
Tue Mar 4 04:38:24 CET 2014


In article 
<CAKJDb-OwrgCiTXZmBuzw534sHhsY5CjMLAfcnO+6rDKrzbEJyw at mail.gmail.com>,
 Zachary Ware <zachary.ware+pylist at gmail.com> wrote:
> On Mon, Mar 3, 2014 at 3:48 PM, Zachary Ware
> <zachary.ware+pylist at gmail.com> wrote:
> > It could be argued that Pip could compile any .py files that it
> > installs and just start screaming if it gets any SyntaxError, but what
> > if your package (for some weird reason) relies on .py file with bad
> > syntax? 
> Somehow, I missed that this is exactly what seems to be happening,
> sans screaming.  So yes, Pip is doing this slightly wrong, but it's
> still on the package author to fix it properly.  But it's still not a
> Python issue, since Pip is still a separate project.

FTR, pip is not doing anything wrong: see the updates to Issue20846 and 
the discussion on python-dev.  The "syntax error" messages displayed are 
warnings which originate from Distutils (which is called by pip and 
other installers) when it tries to byte-compiles the installed files, 
which actually do install successfully.  Byte-compiling is merely an 
optimization and installs do not (and should not) depend on them.  But 
just because a package installs without error doesn't mean it executes 
without error.  The real problem is that the package that was trying to 
be installed with Python 3 is not compatible with Python 3 but there is 
currently no way for pip or any other installer to know that, other than 
perhaps by running a package's test suite if one is provided.  The 
package author could include metadata hints ("Requires-Python") about 
which versions of Python are supported by the package but those optional 
hints aren't used today by any installer.  Having more usable and 
reliable metadata is a focus of packaging PEPs in various stages of 
design and development.  The goal is that eventually installers would be 
able to detect Python version mismatches.  Today it is up to the person 
installing a package to determine that.

-- 
 Ned Deily,
 nad at acm.org




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