Issue1670

Implicit Decimal conversion fails 

Jython 2.5.2rc2 (Release_2_5_2rc2:7167, Oct 24 2010, 22:48:30) 
[Java HotSpot(TM) 64-Bit Server VM (Sun Microsystems Inc.)] on java1.6.0_21
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>>> import math
>>> from decimal import Decimal as D
>>> math.fabs(D('23.23'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: fabs(): 1st arg can't be coerced to double

But this works.

>>> math.fabs(float(D('23.23')))
23.23

The problem here is Decimal's __tojava__ method does not handle the case of __tojava__(Double.class). We could fix that in Decimal but what would be better (in this respect) is having Decimal.__tojava__ fallback to super.__tojava__ when it doesn't know how to handle the conversion.

This would fix the problem because PyObject.__tojava__ will try conversion to Double.class via __float__.

We would have to expose __tojava__ on the object class for that fix though (it currently is not exposed to Python code). I'm not sure that's so good either

Philip, I think it would be better if Decimal handles this explicitly rather than expose __tojava__, which seems likely to introduce other issues.

Target beta 4

I ended up doing it all in __tojava__. I hope this doesn't inconvenience anyone.

Alex's approach is good, and is modeled after the similar treatment in datetime classes.

There's the somewhat related issue that 

>>> import math
>>> math.fabs
<java function fabs 0x2>

instead of CPython 2.7

>>> import math
>>> math.fabs
<built-in function fabs>

is what the math function is, which is what caused us to go with __tojava__ to begin with, which confused my thinking about this bug, but that's a larger problem.

Fixed as of https://hg.python.org/jython/rev/d86bf9da41c7