One more quick thought. The first sentence of the Cython tutorial (chapter two of the manual):
The fundamental nature of Cython can be summed up as follows: Cython is Python with C data types. I understand there are thorny corner-cases and even common cases where it's best to break with Python semantics. This may be one of them. But I remembered this sentence in the shower this morning as I was trying to figure out why I so strongly expected Python semantics on operators. I suppose this is more personal reflection, though, since I'm fine if it remains C semantics -- as long as it is clearly documented. Perhaps a Wiki page, FAQ entry, and/or manual entry of differences between Cython and Python. Thanks! - Ryan Ryan Hinton wrote: > Robert, > > Since I hit the problem I'm motivated to chime in. I also followed the > email trail on the cython list. > > Quick summary: > > [X] Let the programmer decide, with > [X'] Get 4 as the default > > There are obviously some cases where speed is paramount and others where > Python compatibility is paramount, so it would be nice to choose. > Echoing the cython list, I also prefer in-code directives over compiler > options (though the two need not be mutually exclusive -- just a matter > of development time). > > But given the ability to choose, you still need a "default": which > semantics are operative without any compiler options or pragmas. Even > though I "grew up" writing C, I came to Cython gradually from Python > code, making small changes to see what speed-ups I could get. So I > assumed Python semantics were operative. Besides my use case and > personal preference, I think it's more pleasant to add a pragma from a > wiki page of optimizations than to get really frustrated debugging > because you made one little change and now your code segfaults (my > experience). > > Thanks for working on this! > > - Ryan > > Robert Bradshaw wrote: >> Here's a quick poll. >> >> In Python, if I write "-1 % 5", I get 4. This is how we do it in Sage >> as well (and I think it's the right way--that's not what I'm trying >> to ask). However, in C if I write "-1 % 5" I get -1. The question is, >> what should I get in Cython if I write (a % b) where a and b are cdef >> ints? Should I >> >> [ ] Get 4, because it should behave just like in Python, even though >> it will require extra logic and be a bit slower >> >> [ ] Get -1, because they're C ints, and besides we wouldn't be using >> Cython if we didn't care about performance >> >> [ ] Let the programmer decide (e.g. using http://wiki.cython.org/ >> enhancements/compilerdirectives ) recognizing that % will mean >> different things in different contexts. >> >> - Robert >> >> > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
