This code will replicate the problem when run using the latest sympy
pull:
from sympy import Basic
from sympy.printing.str import StrPrinter
from sympy.printing.pretty.pretty import PrettyPrinter, xsym, pprint
class GreenEggsAndHam(Basic):
def __init__(self, string):
self.s = string
def _pretty_(self):
return print_GreenEggsAndHam(self)
class HamPrinter(PrettyPrinter):
printmethod = '_pretty_'
def _print_GreenEggsAndHam(self, e):
return e.s.lower() + xsym('*') + "\xC2\xB7"
def print_GreenEggsAndHam(e):
pp = HamPrinter()
return pp.doprint(e)
MyBreakfast = GreenEggsAndHam('I LOVE SYMPY')
print_GreenEggsAndHam(MyBreakfast)
pprint(MyBreakfast)
~Luke
On Jun 25, 11:58 am, Ondrej Certik <ond...@certik.cz> wrote:
> On Thu, Jun 25, 2009 at 12:50 PM, Luke<hazelnu...@gmail.com> wrote:
>
> > I'm trying to subclass the StrPrinter and PrettyPrinter so that I can
> > customize the display of some classes I have created for PyDy. I have
> > had success with getting StrPrinter, but I found it to have some weird
> > unicode issues, so I am using plain old strings for my sublcass of
> > StrPrinter, and would like to reserve all unicode stuff for the
> > PrettyPrinter.
>
> > The way I am subclassing StrPrinter is as follows:
> > 1) My PyDy classes are subclassed from Basic. I override the __str__()
> > method of each of my PyDy classes to look like:
> > def __str__(self):
> > return pydy_str(self)
>
> > where pydy_str(self) looks like:
> > def pydy_str(e):
> > p = PyDyStrPrinter()
> > return p.doprint(e)
>
> > 2) I subclass StrPrinter, and add methods entitled
> > _print_<MyPyDyClass>, as follows:
> > def _print_UnitVector(self, e):
> > ....
>
> > These _print_*** methods return a string of how I want each class to
> > be displayed.
>
> > Nowhere in any of my classes, or in my subclassing of StrPrinter, do I
> > have printmethod defined. Everything above works just fine.
>
> > The problem is when I try the same approach with subclassing
> > PrettyPrinter. I created class methods entitled _sympypretty_() for
> > each of my classes, then define a pydy_pretty() function, and then
> > subclass PrettyPrinter, analogously to my approach above. It doesn't
> > work. Specifically, I get infinite recursion runtime errors. I tried
> > adding the printmethod class attribute to my PyDyPrettyPrinter, but it
> > didn't make any difference, I still get infinite recursion errors.
>
> > I have spent many hours on this and I am sure it is probably a very
> > simple fix and that I am just not using things correctly. Does
> > anybody have any recommendations on how this should be done properly?
> > Ideally, some example code would be the best that way there would be
> > no confusion as to how this should be done.
>
> > It seems to me that the approach that should be taken to subclassing
> > either StrPrinter or PrettyPrinter should be conceptually the same,
> > but perhaps this isn't the case?
>
> > Also, is the approach I am using above for customizing the StrPrinter
> > the recommended way to do it?
>
> Please create a new branch in your repository with the above problem
> and show here how to reproduce it, so that people can have a look.
>
> Ondrej
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