State
Explore how to implement the state pattern in Python to represent domain states as objects with behavior rather than simple data values. Learn to improve code readability and maintainability by distributing responsibilities across state classes, handling state transitions explicitly, and avoiding complex conditional logic in your Python applications.
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The state pattern is a behavioral pattern that is a clear example of reification in software design, making the concept of our domain problem an explicit object rather than just a side value (for example, using strings or integer flags to represent values or managing state).
Working with an example
When studying unit testing, we had an object that represented a merge request, and it had a state associated with it (open, closed, and so on). We used an enumeration to represent those states because, at that point, they were just data holding a value (the string representation of that particular state). If they had to have some behavior, or the entire merge request had to perform some actions depending on its state and transitions, this would not have been enough.
The fact that we are adding behavior, a runtime structure, to a part of the code has to make us think in terms of objects, because that's what ...