Issue1198

Java integration's py2float doesn't consider __float__ for conversion. 
This is an issue with other conversions (py2int, etc) and likely affects  
more than the math module

Jython 2.5b0+ (trunk:5722:5725M, Dec 9 2008, 16:06:58) 
[Java HotSpot(TM) 64-Bit Server VM (Apple Inc.)] on java1.6.0_07
Type "help", "copyright", "credits" or "license" for more information.
>>> class F(object):
... 	def __float__(self):
... 		return 1.6
... 
>>> import math
>>> math.cos(F())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: cos(): 1st arg can't be coerced to double

Python 2.5.2 (r252:60911, Apr 22 2008, 12:00:45) 
[GCC 4.0.1 (Apple Computer, Inc. build 5367)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> class F(object):
...     def __float__(self):
...             return 1.6
... 
>>> import math
>>> math.cos(F())
-0.029199522301288815

This is breaking a couple SymPy tests:

_______________ sympy/utilities/tests/test_lambdify.py:test_trig  
_______________
File "/home/ondra/repos/sympy/sympy/utilities/tests/ 
test_lambdify.py",
line 150, in test_trig
  d = f(pi)
File "<string>", line 1, in <lambda>
TypeError: cos(): 1st arg can't be coerced to double
_________________________________________________________

This needs to be done in PyObject#__tojava__, since that's what
ReflectedArgs#matches calls. I have a preliminary patch.

Originally I was thinking we'd use the Py.py2int/float methods to do it 
as that's where the current conversions generally happen. Looking at 
them again, though, they are pretty lame:

    public static int py2int(PyObject o, String msg) {
        if (o instanceof PyInteger) {
            return ((PyInteger) o).getValue();
        }
        Object obj = o.__tojava__(Integer.TYPE);

PyInteger.__tojava__ would already do this for us

I have attached a patch, including a minimal test (based on the bug
report). We may want to reconsider how it uses AttributeError, but any
such alternative would presumably require a larger change.

applied in r6109. we should support faux-ints too but it breaks stuff (see 
the comment in PyObject.__tojava__)