Re: [RFC] Edk2 BaseTools Python3 Migration Update

[Laszlo Ersek <lersek@redhat.com>]

On 01/08/19 19:05, Carsey, Jaben wrote:
> 
> 
>> -----Original Message-----
>> From: Laszlo Ersek [mailto:lersek@redhat.com]
>> Sent: Tuesday, January 08, 2019 9:26 AM
>> To: Carsey, Jaben <jaben.carsey@intel.com>; Gao, Liming
>> <liming.gao@intel.com>; Ni, Ray <ray.ni@intel.com>; edk2-
>> devel@lists.01.org; leif.lindholm@linaro.org; afish@apple.com; Kinney,
>> Michael D <michael.d.kinney@intel.com>
>> Subject: Re: [edk2] [RFC] Edk2 BaseTools Python3 Migration Update
>> Importance: High
>>
>> On 01/08/19 17:22, Carsey, Jaben wrote:
>>> Liming and Laszlo,
>>> 	What if we add a 4th option to the environment variable - the path to
>> a specific python interpreter for use.
>>
>> I thought of that, but how do the build tools derive the python version
>> just from the pathname of the interpreter?
>>
>> Will they run "$INTERPRETER --version" and parse the output?
>>
>> I think that could be brittle; distributions sometimes customize the
>> version strings of their executables. The "--version" output is usually
>> human-readable, not machine-readable (per intent).
> 
> Laszlo, you lost me. How is that related to an exact path?   If the user specifies the path, then always use that specific interpreter.

Sorry, my fault. I've been confused by an *earlier* approach that was
described here:

  https://bugzilla.tianocore.org/show_bug.cgi?id=55#c10
  https://bugzilla.tianocore.org/show_bug.cgi?id=55#c12

In that case, if the user only specified the interpreter path, it would
be clear what *interpreter* to use, however it would not be not clear
what *sub-codebase* from BaseTools to run on that interpreter: the
Python2 one, or the Python3 one.

However, now I remember, from

  https://bugzilla.tianocore.org/show_bug.cgi?id=55#c14
  https://bugzilla.tianocore.org/show_bug.cgi?id=55#c15

that after all, the goal is a single common set of BaseTools source code
that runs on Python2 and Python3 alike. In that regard, I agree that the
interpreter pathname is the *only* input we should take & accept from
the user, and the particular python *language version* need neither be
provided by the user, nor be detected by BaseTools themselves.

Sorry about the confusion!

Thanks,
Laszlo