Python

Python’s context managers are great for resource management and stopping the propagation of leaked abstractions. You’ve probably used it while opening a file or a database connection. Usually it starts with a with statement like this: with open("file.txt", "wt") as f: f.write("contents go here") In the above case, file.txt gets automatically closed when the execution flow goes out of the scope. This is equivalent to writing: try: f = open("file.txt", "wt") text = f.write("contents go here") finally: f.close() Writing custom context managers To write a custom context manager, you need to create a class that includes the __enter__ and __exit__ methods. Let’s recreate a custom context manager that will execute the same workflow as above. ...

Recently, my work needed me to create lots of custom data types and draw comparison among them. So, my code was littered with many classes that somewhat looked like this: class CartesianPoint: def __init__(self, x, y, z): self.x = x self.y = y self.z = z def __repr__(self): return f"CartesianPoint(x = {self.x}, y = {self.y}, z = {self.z})" print(CartesianPoint(1, 2, 3)) >>> CartesianPoint(x = 1, y = 2, z = 3) This class only creates a CartesianPoint type and shows a pretty output of the instances created from it. However, it already has two methods inside, __init__ and __repr__ that do not do much. ...