I would say that it's fine, especially in a subclass. David
On Thu, Jun 4, 2015 at 9:23 AM, Bruno Grenet <bruno.gre...@gmail.com> wrote: > Dear all, > > Many classes in SageMath (most of them? all of them? I don't know...) have > their attributes hidden by a leading `__`. Yet in Python hidden attributes > are never really hidden, since it is possible to access the attribute > `__hidden` of the class `MyClass` as `_MyClass__hidden`. > > What SageMath's policy about using these hidden attributes in functions? > > *A concrete example: * > > For sparse polynomials (class `Polynomial_generic_sparse` in > `src/sage/rings/polynomial/polynomial_element_generic.py`), the > coefficients are stored as a dictionary, stored in the attribute > `__coeffs`. To compute the number of nonzero monomials, one can use any of > the following three solutions: > > 1. sage: len(p.coefficients()) # builds the list of (nonzero) > coefficients, and computes its length > 2. sage: len(p.dict()) # copies the dictionary __coeffs and computes > its length > 3. sage: len(p._Polynomial_generic_sparse__coeffs) # computes the > length of __coeffs > > As one can expect, the fastest is solution 3. To get an idea of the > differences, with a random degree-10000 polynomial over ZZ, I get using > `timeit`: > > 1. 1.11 ms > 2. 174 µs > 3. 88 ns (with slowest run 46.05 times longer than fastest) > > Thus if I implement a method `number_of_terms` in the class > `Polynomial_generic_sparse`, I am tempted to implement the third solution. > But is referring to a hidden attribute an issue? > > Cheers, > Bruno > > -- > You received this message because you are subscribed to the Google Groups > "sage-devel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-devel+unsubscr...@googlegroups.com. > To post to this group, send email to sage-devel@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
