PEP0238 lament

[phil hunt]

On Tue, 24 Jul 2001 21:46:15 GMT, Guido van Rossum <guido at python.org> wrote:
>
>(2) A command line option to change division semantics.  I propose
>    -Dnew to make the new division semantics the default, -Dold to
>    make the old semantics the default.  -Dold will be the default
>    until the wait period is over, then -Dnew will become the
>    default.  The -D option is retired when nobody needs -Dold any
>    more.  Modules that contain a future statement always use the new
>    default; there's no way to force the old default on a *per-module*
>    basis (since that would be a language feature that could never be
>    removed).

How about having two executables, 'oldpython' and 'newpython' which
correspond to -Dold and -Dnew.

Furthermore, since 'oldpython' is the same as the existing 'python',
let's rename it 'python'.

We also might be dealing with a mixture of new and old code, so
lets furthermore have a rule that modules ending in .py are by
default compiled with 'python' and modules ending in .ny are
compiled with 'newpython'; in both cases they compile to the
same .pyc format.

In this way, newpython can cope with any change to the nature
of the language, however outlandish (like including $ before
variable names :-)) without breaking a single line of existing
code.

And people can gently "dip their toe into the water" of the new features,
without having to immediately go all the way.


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