On Wednesday, June 13, 2012 2:44:58 PM UTC+2, David Joyner wrote: > > On Wed, Jun 13, 2012 at 8:31 AM, Ronan Lamy wrote: > > Le mercredi 13 juin 2012 à 02:06 -0700, Aleksandar Makelov a écrit : > >> Hi again, > >> > > ... > > > > >> - remove the checks from Perm, and make a *function* PermS (the name > >> is deliberately chosen to be as close as Perm) that performs the > >> checks and then constructs a permutation object using Perm (the name > >> comes from Permutation Safe). > > > > Urgh, no! The design is OK, though not terribly consistent with the rest > > of sympy where users need to directly call class constructors all the > > time, but the naming seems designed to maximise user confusion. Casual > > users shouldn't need to know about the concept of permutation > > "safeness", nor have to remember a cryptic abbreviation for it, and > > functions names (conventionally lowercase) shouldn't make them look like > > classes. > > > I'm a little confused. Is PermS a user function? I thought it was > internal. > If it is internal, and not a function for the casual user, then it > might be renamed _PermS, so it doesn't pop up in tab completion. > > > > Using Perm in Permutation is a bit ugly, but it is endorsed by Knuth (quote which I found in http://www.xact.es/xPerm/index.html)<http://www.xact.es/xPerm/index.html> ''Following a suggestion of Vaughan Pratt, we adopt the convention that perm = permutation, perhaps thereby saving millions of syllables in future research.''
I can accept that PermS be used to create safely permutations, along with Perm which creates them without checking, although I would then use only PermS, since I care about the checks; it is a place less to check if I have a bug. If I need speed I use _new_from_array_form, which is faster than the proposed Perm. I am strongly against _PermS, which is not convenient to type. -- You received this message because you are subscribed to the Google Groups "sympy" group. To view this discussion on the web visit https://groups.google.com/d/msg/sympy/-/GuuO26Bcu1MJ. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
