[Python-Dev] Re: Future division detection (original) (raw)

Greg Ewing greg@cosc.canterbury.ac.nz
Thu, 08 Nov 2001 12:29:24 +1300 (NZDT)

com-nospam@ccraig.org (Christopher A. Craig):

I would like to have an rational cast back to a integer iff (1) the denominator is 1 and (2) future division is active.

If I don't check (2) then I get the situation that if future division is inactive then (rational('1/3')*3)/5 would yield 0 instead of 1/5.

I think what you're asking is impossible. Remember that "future division is active" is a compile-time, per-module notion. Some parts of the code may be doing old-style divisions and other parts new-style divisions. In the above example, at the time when you do the multiplication by 3, there is no way of knowing what sort of division might be performed on the result at some later time, maybe in another module where the future division option was set differently.

Greg Ewing, Computer Science Dept, +--------------------------------------+ University of Canterbury, | A citizen of NewZealandCorp, a | Christchurch, New Zealand | wholly-owned subsidiary of USA Inc. | greg@cosc.canterbury.ac.nz +--------------------------------------+