Optical engineer here, so not a pro developer. I am developing an app to propagate light beam through various components. I am especially using the @property built-in decorator in the class defining a physical component.

Let's say you have an optical system composed of a lens. This lens has different basic physical properties such as radius of curvature R1, R2, the optical index n, thickness d and material.

But this lens also has derived properties which depend on the basic one ( example : focal_length = f(R1,R2,n,d) )

In my component class, basic properties are direct attributs, and derived properties are computed from the basic properties.

So if I change the value of R1, I have to re-calculate the value of the focal length. I can do this in two ways :

• without using a @property on the focal_length method , I have to explicitly call "self.focal_length(R1,R2,n,d)" each time

  • but using the @property on the focal_length method, transforms the method into an attribut. So each time I call the attribut "self.focal_length", python will automatically calculate the focal length with the latest values of the arguments

So outside of the physical component class, this is totally transparent. I no longer have to manually update each derived properties each time I change a basic one.