Because, if you assume that each class has is_Class set to True for itself, you can just use getattr(object, 'is_Class', False) (sorry, I meant getattr(), not hasattr()). For __getattr__, you could set that in Basic and make it recognize is_Class. I don't know if that will still have the speed of the direct is_Class that we are having now, but it least it could handle classes that Basic doesn't know about.
Aaron Meurer On Sep 23, 2010, at 8:21 PM, Andy Ray Terrel wrote: > How would hasattr help you? It doesn't tell you if there is a > instance of a class in the arg tree only if the instance has a > specific attribute. I guess nobody has needed __getatrr__ yet. > > -- Andy > > On Thu, Sep 23, 2010 at 8:50 PM, Aaron S. Meurer <asmeu...@gmail.com> wrote: >> How does the speed compare if you use hasattr()? Also, is there a good >> reason that Basic doesn't have __getattr__() implemented? >> >> Aaron Meurer >> >> On Sep 23, 2010, at 7:42 PM, Andy Ray Terrel wrote: >> >>> The problem with the is_Foo construct is that every basic has to carry >>> it, so every object grows. The reason (maybe historic) there are some >>> there is that its faster to ask is_Foo than to do isinstance a lot and >>> the core needs some faster things. For bits that aren't checked very >>> much we should try to keep it out of the core (maybe put it in the >>> assumptions). >>> >>> Of course once Indexed elements start propogating to other modules it >>> might be necessary to do this. For now I vote that we either include a >>> depth first search for the properties. >>> >>> -- Andy >>> >>> On Thu, Sep 23, 2010 at 6:27 PM, Nicholas Kinar <n.ki...@usask.ca> wrote: >>>> >>>>> You should also know about pre/post_order_traversal (both must be imported >>>>> from sympy.utilities.iterables), which let you dig all the way down in an >>>>> expression tree. >>>>> >>>>> In [109]: from sympy.utilities.iterables import preorder_traversal, >>>>> postorder_traversal >>>>> >>>>> In [110]: preorder_traversal(sin(x**2) + 4*x**3) >>>>> Out[110]:<generator object preorder_traversal at 0x102415a00> >>>>> >>>>> In [111]: list(preorder_traversal(sin(x**2) + 4*x**3)) >>>>> Out[111]: >>>>> ⎡ ⎛ 2⎞ 3 3 3 ⎛ 2⎞ 2 ⎤ >>>>> ⎣sin⎝x ⎠ + 4⋅x , 4⋅x , 4, x , x, 3, sin⎝x ⎠, x , x, 2⎦ >>>>> >>>>> In [112]: list(postorder_traversal(sin(x**2) + 4*x**3)) >>>>> Out[112]: >>>>> ⎡ 3 3 2 ⎛ 2⎞ ⎛ 2⎞ 3⎤ >>>>> ⎣4, x, 3, x , 4⋅x , x, 2, x , sin⎝x ⎠, sin⎝x ⎠ + 4⋅x ⎦ >>>>> >>>>> Also, as Chris said, using .atoms() to find what IndexedElements there are >>>>> is useful. There maybe ought to be some .is_IndexedElement attribute on >>>>> IndexedElement, just as there is for every other major class. Øyvind, >>>>> what >>>>> do you think? >>>>> >>>>> Aaron Meurer >>>>> >>>>> >>>> >>>> Thanks, Aaron; I also agree that there should be some way to check and see >>>> if a class is of a particular type, and it would be terrific if >>>> IndexedElement would also have this. >>>> >>>> Nicholas >>>> >>>> -- >>>> You received this message because you are subscribed to the Google Groups >>>> "sympy" group. >>>> To post to this group, send email to sy...@googlegroups.com. >>>> To unsubscribe from this group, send email to >>>> sympy+unsubscr...@googlegroups.com. >>>> For more options, visit this group at >>>> http://groups.google.com/group/sympy?hl=en. >>>> >>>> >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "sympy" group. >>> To post to this group, send email to sy...@googlegroups.com. >>> To unsubscribe from this group, send email to >>> sympy+unsubscr...@googlegroups.com. >>> For more options, visit this group at >>> http://groups.google.com/group/sympy?hl=en. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To post to this group, send email to sy...@googlegroups.com. >> To unsubscribe from this group, send email to >> sympy+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/sympy?hl=en. >> >> > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To post to this group, send email to sy...@googlegroups.com. > To unsubscribe from this group, send email to > sympy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sy...@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
