On 6/22/05, Michael McLay <mclay@python.net> wrote:
This idea is dead on arrival. The change would break many applications and modules. A successful proposal cannot break backwards compatibility. Adding a dpython interpreter to the current code base is one possiblity.
Is there actually much code around that relies on the particular precision of 32- or 64-bit binary floats for arithmetic, and ceases working when higher precision is available? Note that functions like struct.pack would be unaffected. If compatibility is a problem, this could still be a possibility for Python 3.0. In either case, compatibility can be ensured by allowing both n-digit decimal and hardware binary precision for floats, settable via a float context. Then the backwards compatible binary mode can be default, and "decimal mode" can be set with one line of code. d-suffixed literals create floats with decimal precision. There is the alternative of providing decimal literals by using separate decimal and binary float base types, but in my eyes this would be redundant. The primary use of binary floats is performance and compatibility, and both can be achieved with my proposal without sacrificing the simplicity and elegance of having a single type to represent non-integral numbers. It makes more sense to extend the float type with the power and versatility of the decimal module than to have a special type side by side with a default type that is less capable. Fredrik