Hi,
I am new here and relatively new to Python, so be gentle:
Is there a recommended generic implementation of __repr__ for objects
equal by value to assure that eval(repr(x)) == x independet of which
module the call is made from?
Example:
class Age:
def __init__(self, an_age):
self.age = an_age
def __eq__(self, obj):
self.age == obj.age
def __repr__(self):
return self.__class__.__name__ + \
"(%r)" % self.age
age_ten = Age(10)
print repr(age_ten)
print eval(repr(age_ten))
print eval(repr(age_ten)).age
Running this gives
Age(10)
Age(10)
10
Exactly as I want to.
The problem arises when the Age class is iomported into another module
in another package as then there is a package prefix and the above
implementation of __repr__ does not work.
I have then experimented with doing somthing like
def __repr__(self):
return self.__module__ + '.' + self.__class__.__name__ +
"(%r)" % self.age
This seems to work when called from the outside, but not from the
inside of the module. That is, if I rerun the script above the the
module name prefixed to the representation I get the following error
Traceback (most recent call last):
File "valuetest.py", line 15, in <module>
print eval(repr(age_ten))
__main__.Age(10)
File "<string>", line 1, in <module>
NameError: name '__main__' is not defined
This is pretty annoying.
My question is: Is there a robust generic type of implementation of
__repr__ which I can use instead?
This is something I plan to reuse for many different Value classes, so
I would like to get it robust.
Thanks,
Slaunger
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