Backward compatibility environments (was Future division patch available)

[Chris Barker]

Erik Max Francis wrote:

> Agreed.  Let's try categorizing the Python environments which will have
> different ramifications for a backward-incompatible change:
> 
> 1.  First and easiest is code that is in active use which can be changed
> in place after an upgrade to Python 238 (what I'll use to refer to a
> version of Python which implements PEP 238 and/or requires PEP 238's
> semantics).
> 
> 2.  Code that is established and in long-term use which is not in active
> use but which still has resources that can be thrown at it to update it.
> 
> 3.  Code that is established and in longer-term use but which is not in
> a position to be fixed by the original engineers, either because it has
> been passed around repeatedly or because it is, say, at a client side
> that no longer has any contact with the original company (presumably
> because pre-238 Python has been so reliable that there was no need :-).
> 
> 4.  Code which may be in use and up to date but which is not trivially
> available in editable source form and/or from which compatibility
> warnings may not be easily found, such as stowed in a database or in
> 
> 5.  Code running in very special environments in which the ramifications
> of PEP 238 may not even make sense.  What does always-float division
> mean on an architecture that does not support floats of any kind (say,
> on an architecture with no FPU and with limited space so that software
> emulation was deemed wasteful)?

You forgot:

6.  Code taht is being curretnly maintained, but which needs to run on
both old and new versions of the interpreter.

-Chris


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Christopher Barker,
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