how to call a function in Python in another function?

Hi I am trying to call a function on change of an attribute of a class, how can i do this in Python?

• Answer:

  Going off of the following in the comment section: Will post the example in some time...for now..assume there is a attribute date, so when i set it to todays date..another attribute year should be automatically populated to year of the date.. There are a couple of ways of doing this, but the obvious ones involve properties. Properties combine accessor (getter), mutator (setter) and destructor methods of an object into a single sub-object. Or, to put it another way, properties combine a collection of methods into an interface that looks like a single public variable. So: class SampleClass(object): def __init__(self, sample_date): self.sample_date = sample_date @property def sample_date_year(self): return self.sample_date.year if __name__ == '__main__': from datetime import date sc = SampleClass(date(2013, 1, 1)) print(sc.sample_date_year) sc.sample_date = date(2112, 1, 1)) print(sc.sample_date_year) >>> 2013 >>> 2112 Notice how even though sample_date_year looks like a method of SampleClass, we don't actually have to call it to get the year's output. This is certainly a workable solution - but you'll notice it still involves referencing sample_date.year every time we access sample_date_year. This really shouldn't be an issue, but let's say you're really trying to cut down on lookups because you desperately (cannot emphasize the word "desperately" enough) need higher performance. What you can do is start messing around with mutators, as well: class SampleClass(object): def __init__(self, sample_date): self.sample_date = sample_date @property def sample_date(self): return self._sample_date @sample_date.setter def sample_date(self, sample_date): self.sample_date_year = sample_date.year self._sample_date = sample_date This second way is, in my opinion, overkill for the problem at hand, but there are other problems where it may be the obvious choice. Here's the documentation, check it out: http://docs.python.org/2/library/functions.html#property