exec

Rolf Wester rolf.wester at ilt.fraunhofer.de
Thu Mar 1 18:23:58 CET 2012


Thank you, that really made things much easier and admittedly much less nasty too.

Regards
Rolf

On 01/03/12 18:14, Peter Otten wrote:
> Rolf Wester wrote:
> 
>> The reason to use exec is just laziness. I have quite a lot of classes
>> representing material data and every class has a number of parameters.
>> The parameter are Magnitude objects (they have a value and a unit and
>> overloaded special functions to correctly handle the units). I want to
>> have getter functions that either return the Magnitude object or just the
>> value:
>>
>> iron = Iron()
>> iron.rho(0) => value
>> iron.rho() => Magnitude object
>>
>> def rho(self, uf=1):
>>     if uf == 1:
>>         return self._rho
>>     else:
>> return self._rho.val
>>
>> And because this would mean quite a lot of writing I tried to do it with
>> exec.
> 
> Make the Magnitude class callable then:
> 
>>>> class Magnitude(object):
> ...     def __init__(self, value):
> ...             self.value = value
> ...     def __call__(self, uf=1):
> ...             if uf == 1:
> ...                     return self
> ...             return self.value
> ...
>>>> class Iron(object):
> ...     def __init__(self):
> ...             self.rho = Magnitude(42)
> ...
>>>> iron = Iron()
>>>> iron.rho()
> <__main__.Magnitude object at 0x7fb94062be10>
>>>> iron.rho(0)
> 42
> 
> 



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