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POPython: preferred way to handle large number of attributes that might not exists?
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copied!<p>EDIT: The original problem involves PyQt and matplotlib and the real question is too complicated to explain, so I tried to simplify it and it didn't really work out. But from the replies I learned the actual problem might lie somewhere else than what I originally thought. I guess this is what learning to program is about.</p> <p>Thanks everyone!</p> <hr> <p>I'm facing a stylistic problem that bothers me. I tried to make is as general as possible to be helpful to others as well. Consider the following class:</p> <pre><code>class Values(object): def __init__(self): self.first_attr = None self.second_attr = None self.third_attr = None self.fourth_attr = None def set_first(self, data): self.first_attr = data def set_second(self, data): self.second_attr = data def set_third(self, data): self.third_attr = data def set_fourth(self, data): self.fourth_attr = data def add_to_three(self): attrs = ( self.first_attr, self.second_attr, self.third_attr, ) self._add_one(attrs) def add_to_two(self): attrs = ( self.second_attr, self.fourth_attr, ) self._add_one(attrs) def _add_one(self, attrs): for attr in attrs: if attr: attr += 1 </code></pre> <p>We have a class of values. The class can have a total of 4 attributes of different values. Each value can be set with a setter (didn't use decorators to simplify things).</p> <p>There are also two methods that have a tuple of attributes whose value should be increased. These values are determined before run time. </p> <p>We also have a method "add_one" that adds one to those attributes that it receives if those attributes are set. Otherwise nothing should happen.</p> <p>Now let's create a couple instances and set some values</p> <pre><code>first_values = Values() first_values.set_second = 5 first_values.add_to_three() second_values = Values() second_values.set_first = 2 second_values.set_third = 4 second_values.add_to_two() </code></pre> <p>This works fine, because the "add_one" method checks if each attribute is set.</p> <p>But what if I have 50 attributes? I don't like the idea of setting them all to None. Also, I don't like the idea of explicitly writing the tuples in those add_to_ methods.</p> <p>What would be the most proper way to handle this if there are lots of attributes by changing only the Values class?</p>

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