When to use class versus dict in python? [closed]

Question

When considering design, in which cases does it make sense to use class versus dict? Pros & Cons would be useful too.

For example,

class AlbumState:     """ AlbumState class, tracks photos shown, etc"""      def __init__ (self, album):         """ album for this object will track state"""         self.album = album          self.photos_shown = []         self.photos_notshown = range(album.size()) 

versus

albumstate['album'] = album albumstate['photos_shown'] = [] albumstate['photos_notshown'] = range(album.size()) 

Answer 1

I would say the first and most important criteria to distinguish whether to use a class or a dictionary is whether you just want to have some data storage or you also want to have some logic (i.e., methods).

If you only need to keep together several data, then a dictionary might be the way to go. On the other hand, if you need operations performed on that data, and there is a very tight relationship between the data and the operations (forming a kind of entity), then that really calls for using a class.

As @Ben is suggesting, you may start using just a dictionary when you have a bunch of related data, and if at some point your realize that you also need some logic for that data, you can turn the dictionary into a class.

You may also have a look at the Unified Modeling Language (UML) and its class diagrams to get a better feeling on how to use classes. If you are just doing some scripting or programming a small application you may not need to use UML, but if you are designing a bigger and more complex system, it can really help you to decide what and how many classes do you need beforehand.