On 7/28/2014 7:08 AM, Thomas Heller wrote:
> I cannot compare signals containing enum instances; this looks like a
> bug to me:
>
> c:\Users\thomas\ip>py -2.7-32
> Python 2.7.7 (default, Jun 1 2014, 14:17:13) [MSC v.1500 32 bit
> (Intel)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import myhdl
> >>>
> >>> state = myhdl.enum("foo", "bar")
> >>>
> >>> a = myhdl.Signal(state.foo)
> >>> b = myhdl.Signal(state.bar)
> >>>
> >>> print a == b
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "C:\Python27\lib\site-packages\myhdl\_Signal.py", line 479, in
> __cmp__
> return cmp(self._val, other)
> File "C:\Python27\lib\site-packages\myhdl\_enum.py", line 109, in
> _notImplementedCompare
> raise NotImplementedError
> NotImplementedError
> >>>
>
Yes, I would agree this is unexpected behavior.
The problem is the use of the "cmp" function in
the Signal class. The cmp(x, y) [1] function performs
a x > y which is not implemented in the enum class
(good reason). The use-case of a Signal(enum) ==
Signal(enum) probably has not been used, but I agree
it is a valid case.
import myhdl
state = myhdl.enum("foo", "bar")
a = myhdl.Signal(state.foo)
b = myhdl.Signal(state.bar)
print a == state.foo
print a == state.bar
print b == state.foo
print b == state.bar
print a == b
Only the Signal(enum) == Signal(enum) fails because the
Signal comparison calls. This should be added as an issue
in the repo tracker [2].
Regards,
Chris
[1] https://docs.python.org/2/library/functions.html?highlight=cmp#cmp
[2] https://bitbucket.org/jandecaluwe/myhdl/issues?status=new&status=open
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