Making Variable Text Output More Pythonic?

[Arnaud Delobelle]

afrobeard <afrobeard at gmail.com> writes:

> Arnaud's code wont work if self.opt1 is None, an empty list, an empty
> tuple, False, etc, because all these evaluate to false. They wont
> print the internal state of these variables. [Just an informational
> notice, this may be the behavior you expect]

??? My suggestion is to get rid of attributes altogether and does not
test any truth values.

> Secondly, I'm not sure if you know the variable names from before hand
> in which case Casey's approach will work, or you need to know them via
> introspection. http://www.ibm.com/developerworks/library/l-pyint.html
> [Scroll down to attributes].
>
> On May 16, 1:44 am, Arnaud Delobelle <arno... at googlemail.com> wrote:
>> Casey <casey.mcgi... at gmail.com> writes:
>> > Hi,
>>
>> > I have some classes that print variable outputs depending on their
>> > internal state, like so:
>>
>> > def __str__(self):
>> >     out = []
>> >     if self.opt1: out += ['option 1 is %s' % self.opt1']
>> >     if self.opt2: out += ['option 2 is %s' % self.opt2']
>> >     ....
>> >     return '\n'.join(out)
>>
>> > Is there any way to make this cleaner?
>>
>> Maybe.
>>
>> Have a dictionary of options rather than individual attributes;
>> options not in the dictionary are not set. E.g.
>>
>> mask = {
>>     'opt1': 'option 1 is %s',
>>     'opt2': 'option 2 is %s',
>>     ...
>>     }
>>
>> def __str__(self):
>>     return '\n'.join(mask[o] % v for o,v in self.options.iteritems())
>>
>> --
>> Arnaud