Software design and clean code: Python

Sefism.Software design and clean code: Python

Tauseef Fayyaz

A to Z

Glossary

Every concept in this sheet, plus the smaller terms it uses. Select a concept to open its card.

A

Abstraction: Showing callers what something does and hiding how it does it.

C

Class and object: A class is a blueprint that bundles data (fields) with the behaviour that works on it (methods).
Composition over inheritance: Building a class by holding other objects and delegating to them (has-a) rather than by extending a parent (is-a).

D

Dependency injection: Passing an object the things it needs, usually through its constructor, instead of letting it create or look them up itself.
Dependency inversion principle (DIP): High-level policy should not depend on low-level details; both should depend on an abstraction.
DRY, KISS and YAGNI: DRY: every piece of knowledge has one home.

E

Encapsulation: Hiding an object's internal state behind a small public interface, so outside code can only change it through methods that keep its rules (invariants) true.

I

Inheritance: A subclass takes on the fields and methods of a parent class and can add to or override them.
Interface segregation principle (ISP): Clients should not be forced to depend on methods they do not use.
Interfaces and abstract classes: An interface lists methods a type promises to provide, with no state.

L

Liskov substitution principle (LSP): A subtype must work anywhere its parent type is expected without surprising the caller: it may not demand more, promise less or throw where the parent would not.

O

Open/closed principle (OCP): Code should be open for extension and closed for modification: you add behaviour by adding new code, such as a new class, rather than editing working code.

P

Polymorphism: One call working on many types: code asks any Shape for its area, and each type answers in its own way.

S

Single responsibility principle (SRP): A class should have one reason to change, meaning it answers to one group of people or one kind of decision.

V

Value objects and immutability: A value object is defined by its values, not an identity: two Money(10, "USD") objects are equal.