Sokolov Yura writes: > Excuse my English No problem. You command of english probably exceeds my command of any other language.
> I think, we could just segregate tokens for decimal and real float and > make them interoperable. > Most of us works with business databases - all "floats" are really > decimals, algebraic operations > should work without float inconsistency and those operations rare so > speed is not important. > But some of us use floats for speed in scientific and multimedia programs. I'm not sure why you say "most" (have you seen some surveys of Python programmers that I haven't seen?), but I think we all agree that there are Python users who rarely have a need for machine floats, and others who badly need them. I'll take your specific suggestions out of order: > with "from __future__ import Decimal" we could: > c) result of operation with decimal operands should be decimal > >>> 1.0/3.0 > 0.33333333333333333 This already works. > d) result of operation with float operands should be float > >>> 1.0f/3.0f > 0.33333333333333331f This already works. > e) result of operation with decimal and float should be float (decimal > converts into float and operation perfomed) > >>> 1.0f/3.0 > 0.33333333333333331f > >>> 1.0/3.0f > 0.33333333333333331f Mixing Decimal and float is nearly ALWAYS a user error. Doing it correctly requires significant expertise in the peculiarities of floating point representations. So Python protects the user by throwing exceptions when attempts are made to mix Decimal and floats. This is the desired behavior (and the experts already know how to work around it in the RARE occasions when they need to). > a) interpret regular float constants as decimal > b) interpret float constants with suffix 'f' as float (like 1.5f > 345.2e-5f etc) There are two different ideas here, which I will separate. The first is a proposal that there be a way to provide Decimal literals. The second proposal is that the ###.### be the literal for Decimals and that ###.###f be the literal for floats. I'm in favor of the first idea. Decimals are useful enough that it would be a good idea to provide some sort of literal for their use. This is well worth a PEP. But if we DO agree that we ought to have literals for both floats and Decimals, then we also need to decide which gets the coveted "unadorned decimal literal" (ie, ###.###). Performance argues in favor of floats (they run *MUCH* faster). Usability (particularly for beginners) argues in favor of Decimals (they sometimes still have surprising behavior, but less often than with binary floats). And backward compatibility argues in favor of floats. Myself, I'm an "expert" user (at least to this extent) and I could easily handle either choice. If others felt like me, then its likely that the backward compatibility argument and the need to fight the pervasive meme that "Python is slow" will win the day. -- Michael Chermside _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
