Clean Code in Python

Container objects

Containers are objects that implement a __contains__ method (that usually returns a Boolean value). This method is called in the presence of the in keyword of Python.

Something like the following:

element in container

When used in Python becomes this:

container.__contains__(element)

You can imagine how much more readable (and Pythonic!) the code can be when this method is properly implemented.

Let's say we have to mark some points on a map of a game that has two-dimensional coordinates. We might expect to find a function like the following:

def mark_coordinate(grid, coord):    if 0 <= coord.x < grid.width and 0 <= coord.y < grid.height:        grid[coord] = MARKED

Now, the part that checks the condition of the first if statement seems ...