PEP 238 (revised)
Guido van Rossum
guido at python.org
Fri Jul 27 16:09:43 CEST 2001
Peter Hansen <peter at engcorp.com> writes:
> Guido van Rossum wrote:
> > Here's a completely revised version of PEP 238.
> > Command Line Option
> > The -D command line option takes a string argument that can take
> > three values: "old", "warn", or "new". The default is "old" in
> > Python 2.2 but will change to "warn" in later 2.x versions. The
> > "old" value means the classic division operator acts as described.
> > The "warn" value means the classic division operator issues a
> > warning (a DeprecatinWarning using the standard warning framework)
> > when applied to ints or longs. The "new" value changes the
> > default globally so that the / operator is always interpreted as
> > true division.
> The choice of command line options is inconsistent with the terminology
> used elsewhere in the updated PEP.
> To further reduce the potential for confusion, I suggest changing
> "old" and "new" to "classic" and "true".
I considered this, but I disagree. I don't think there will be much
confusion since the words "classic" and "true" don't occur in the
source (except when overloading __truediv__). The old/new distinction
makes the arrow of time more obvious.
> If that suggestion is accepted, "warn" might be better spelled
> more like "classic-warn".
> The updated PEP also makes no mention of a utility for scanning
> existing code to check for potential problems. Is this considered
> an intractable problem? Is there any commitment to doing this,
> eventually, as part of the implementation of this PEP? Or is the
> presence of the "warn" option considered sufficient (to allow for
> testing, rather than scanning)?
The PEP can't address everything. I have no idea how to write such a
scanner, and I think it would require type inference of unrivaled
sophistication, so I'm not keen on promising it in the PEP. I assume
there will be some kind of conversion tool, but it's outside the scope
of the PEP.
--Guido van Rossum (home page: http://www.python.org/~guido/)
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