Specially annoying was the fact that you could not return list
or tuples.
I don't know the reason of this behaviour, fortunately
changing it did not break any tests.
---
sympy/core/function.py | 17 ++++++-----------
sympy/core/tests/test_functions.py | 7 +++++++
2 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/sympy/core/function.py b/sympy/core/function.py
index aae869d..8331751 100644
--- a/sympy/core/function.py
+++ b/sympy/core/function.py
@@ -138,18 +138,13 @@ def __new__(cls, *args, **options):
# up to here.
if options.get('evaluate') is False:
return Basic.__new__(cls, *args, **options)
- r = cls.eval(*args)
- if isinstance(r, Basic):
+ evaluated = cls.eval(*args)
+ if evaluated is not None: return evaluated
+ # Just undefined functions have nargs == None
+ if not cls.nargs and hasattr(cls, 'undefined_Function'):
+ r = Basic.__new__(cls, *args, **options)
+ r.nargs = len(args)
return r
- elif r is None:
- # Just undefined functions have nargs == None
- if not cls.nargs and hasattr(cls, 'undefined_Function'):
- r = Basic.__new__(cls, *args, **options)
- r.nargs = len(args)
- return r
- pass
- elif not isinstance(r, tuple):
- args = (r,)
return Basic.__new__(cls, *args, **options)
@property
diff --git a/sympy/core/tests/test_functions.py
b/sympy/core/tests/test_functions.py
index 8d7d165..94b08a6 100644
--- a/sympy/core/tests/test_functions.py
+++ b/sympy/core/tests/test_functions.py
@@ -290,3 +290,10 @@ def eq(a,b,eps):
assert eq(exp(-0.5+1.5*I).evalf(15), Real("0.0429042815937374") +
Real("0.605011292285002")*I, 1e-13)
assert eq(log(pi+sqrt(2)*I).evalf(15), Real("1.23699044022052") +
Real("0.422985442737893")*I, 1e-13)
assert eq(cos(100).evalf(15), Real("0.86231887228768"), 1e-13)
+
+def test_extensibility_eval():
+ class MyFunc(Function):
+ @classmethod
+ def eval(cls, *args):
+ return (0,0,0)
+ assert MyFunc(0) == (0,0,0)
\ No newline at end of file
--
1.6.1.2
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