Don't repeat yourself principle

As explained in The Well-Grounded Python Developer: How the pros use Python and Flask

The DRY principle is the software design principle of avoiding duplicated knowledge or logic in a codebase.

How The Well-Grounded Python Developer: How the pros use Python and Flask covers it

How deep it goes

Explains duplication's maintenance risk and demonstrates inheritance through a growing shape-class hierarchy.

Examples

Uses Shape, Rectangle, Square, and Circle examples, including shared initialization and specialized drawing behavior.

What it assumes

Builds on Python classes while defining parent, child, base class, derived class, superclass, and subclass terminology.

What you can do after

Apply it via inheritance to share common attributes and behavior while specializing child classes.

How it connects

Connects DRY with inheritance, classes, parent classes, child classes, and object-oriented design.

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Also explained in

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  A Pythonic Adventure: From Python basics to a working web appThe DRY principle is the software-development practice of avoiding duplicated knowledge or implementation by defining it once and reusing it.
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  Object-Oriented Software Design in C++The Don't Repeat Yourself Principle states that every piece of knowledge or behavior should have a single authoritative representation in a system.
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  Python Workout: 50 ten-minute exercisesThe software-development principle of avoiding duplicated knowledge or logic by defining it once and reusing it.
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  Effective Platform EngineeringThe DRY principle is the practice of avoiding duplicated knowledge or logic by maintaining a single authoritative representation.
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  Software Design for Python ProgrammersThe Don't Repeat Yourself Principle states that each piece of knowledge or behavior should have a single authoritative representation in code.
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  Pandas Workout: 200 exercises to make you a stronger data analystDon't repeat yourself is a software design principle that avoids duplicating logic or equivalent code.
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  100 C++ Mistakes and How to Avoid ThemThe DRY principle is the software design principle of avoiding repeated knowledge or behavior across multiple implementations.
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  Python How-ToDRY is the software design principle that each piece of knowledge or behavior should have a single authoritative representation.
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  Python Workout, Second EditionThe DRY principle is a software-development principle that avoids duplicating knowledge or logic by expressing it once and reusing it.

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Related concepts

• code duplicationaddressed by · Code duplication is the presence of equivalent or substantially similar source code or implementation logic in multiple locations within a software system.
• inheritanceused by · Inheritance is a mechanism by which a child type or element receives properties, values, or behavior from a parent, subject to system rules and possible overrides.
• decouplingaddresses · Decoupling is the design practice of reducing direct dependencies between software components so they can change, operate, or evolve more independently.
• moduleaddressed by · A module is a distinct, bounded software unit that groups related code or functionality and provides an organizational or interaction boundary within a larger system.
• functionuses · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.

This explainer was generated by Manning's knowledge graph from the text of The Well-Grounded Python Developer: How the pros use Python and Flask. The section links point to the parts of the book it draws on.