On Sun, Jun 29, 2008 at 2:16 PM, Kirill Smelkov <[EMAIL PROTECTED]> wrote: > > All, > > On Sat, Jun 28, 2008 at 12:49:44PM +0200, Ondrej Certik wrote: >> Sorry for top posting, writing from a cell phone. I think we need to >> implement all printing ways we mentioned in this thread, probably in >> the Printer class just like pretty printing or latex. Then we will >> just call one in Basic.__str__ and another in Basic.__repr__ and >> remove all other str and repr methods. We can of course discuss which >> one to call from where, but then we'll be just discussing a change of >> exactly one line of code. As to other things, I agree with Fredrik. >> Fredrik, will you come to euroscipy or scipy2008, so that we can fix >> this together? It be awesome. :) All students here, please apply for >> sponsorship to scipy2008, so that enthought has some good students to >> choose from and that we can hack on sympy at Caltech.:) Ondrej >> >> On 6/27/08, Kirill Smelkov <[EMAIL PROTECTED]> wrote: >> > >> > On Fri, Jun 27, 2008 at 11:16:18PM +0200, Fredrik Johansson wrote: >> >> >> >> On Fri, Jun 27, 2008 at 10:56 PM, Kirill Smelkov >> >> <[EMAIL PROTECTED]> wrote: >> >> >> >> > I quote http://docs.python.org/ref/customization.html#l2h-183 >> >> > >> >> > __repr__(self): >> >> > >> >> > Called by the repr() built-in function and by string conversions >> >> > (reverse >> >> > quotes) to compute the ``official'' string representation of an object. >> >> > If at >> >> > all possible, this should look like a valid Python expression that >> >> > could be >> >> > used to recreate an object with the same value (given an appropriate >> >> > environment). If this is not possible, a string of the form "<...some >> >> > useful >> >> > description...>" should be returned. The return value must be a string >> >> > object. >> >> > If a class defines __repr__() but not __str__(), then __repr__() is >> >> > also used >> >> > when an ``informal'' string representation of instances of that class >> >> > is >> >> > required. >> >> >> >> Note "given an appropriate environment". The appropriate environment >> >> is use within SymPy so I think it is actually sufficient if >> >> sympify(repr(x)) == x holds, sympify taking the role of eval. It is >> >> fine in my opinion if repr displays rationals as 2/3, etc. >> >> >> >> > This is typically used for debugging, so it is important that the >> >> > representation is information-rich and unambiguous. >> >> > >> >> > >> >> > So, say about Symbol('x') -> 'x' -- symbols could be Dummy, Temporary, >> >> > they >> >> > could have non-default assumption, etc. >> >> >> >> Yes, and this is something I have pointed out before. It is very >> >> problematic that expressions can have "hidden" properties, that don't >> >> show up in the output of either repr() or str(). My suggested solution >> >> is to remove assumptions from expressions and get rid of >> >> Dummy/Temporary/Wild, just having symbols. >> > >> > Why woudn't str(expr) serve for this? >> > >> > Guys, you are just forcing someone to invent another pairs of methods >> > for which repr/__repr__ were originally invented for. >> > >> > If repr is not that informative there will be some point in time, where >> > this information would be needed, and one (probably me) will have to >> > write say debug/__debug__, but why can't we have this sort of output >> > right from repr? What are cons of this? My point is that there is >> > str(expr) and also we can always use sympy.interactive and ipython. > > Ok, after a bit of thinking, and good idea from Fredrik about > "appropriate context" in repr description, here is what I propose: > > pprint(expr) -- nice looking 2D pretty-printed formula > > str(expr) -- if possible nice loocking 1D formula, and > > sympify(str(expr)) == expr invariant holds > > > repr(expr) -- internal representation of expr with class names and > other details, and > > eval(repr(expr)) == expr invariant holds > > > Sounds reasonable?
Sounds ok to me. But as I said, all printing ways should be really easy to access and also very easy to switch, ideally just one line of code in Basic.__repr__(). Ondrej --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com 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 -~----------~----~----~----~------~----~------~--~---
