[Python-ideas] Specifying Python version

Brice Parent contact at brice.xyz
Thu May 17 05:07:27 EDT 2018

It's in the same spirit as what I proposed in my answer to Guido's crazy 
idea, but set at a different level (in code instead of in setup.py in my 

I think it belongs to the same discussion, so I'm copying it here (sorry 
for the inconvenience if you already read it there):

Le 16/05/2018 à 11:22, Brice Parent a écrit :
> Why not have the compatibility be done at setup.py's level?
> Like having something like this:
> setup(
>     name="LegacyLib",
>     version="8.4.1",
>     ...
>     max_compatibility="3.4"  # Defining here Python's max version for 
> which this lib has been upgraded
> )
> Of course, we may use any other word instead of "max_compatibility", 
> like "designed_for", "python_version", or anything a better English 
> speaker could think of.
> The point is, it would either:
> - when you install the library, rename all variables that are now 
> keywords (we'd know the exact list thanks to max_compatiblity) by 
> suffixing them with "_"
> - or set a flag that will do that when creating the *.pyc files.
> Possible problems/limitations I can already find:
> - There would still be possible errors when using variable names that 
> are generated on the fly (I have no clue how this could ever be addressed)
> - It might get complicated at some point to know what to do, like when 
> we have lib_a in some version depending on lib_b (with or without a 
> max_compatibility version number), it is obvious that lib_a will use 
> lib_b's original variable names (without the appended "_"), but our 
> code which might also want to interact with lib_b would have to.


Le 16/05/2018 à 21:02, MRAB a écrit :
> Instead of verbatim identifiers, how about a special comment giving 
> the Python version in which the file was written?
> There could then be a tool similar to 2to3 that converts the file to a 
> more recent version of Python that might have new reserved words. In 
> most cases the new file would merely be a copy of the original, but 
> with an updated Python version.
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