Tidy First?

1. Tidying First: A Strategic Approach to Software Design

"Software design is an exercise in human relationships."

Tidying first is a strategic approach to software design that focuses on making small, safe structural changes to code before implementing behavior changes. This approach aims to improve code readability, maintainability, and flexibility. Tidyings are mini-refactorings that can be applied quickly and easily, such as:

• Guard clauses
• Explaining variables and constants
• Extracting helper functions
• Normalizing symmetries

The goal of tidying first is to make future behavior changes easier and more efficient. By investing in code structure, developers create options for future changes and reduce the cost of software development over time.

2. The Economics of Software Design: Time Value and Optionality

"A dollar today is worth more than a dollar tomorrow, so earn sooner and spend later."

Time value of money and optionality are two key economic concepts that influence software design decisions. The time value of money suggests that earning revenue sooner and delaying expenses is generally preferable. However, optionality emphasizes the value of creating future possibilities.

In software design, this translates to:

• Balancing immediate behavior changes (revenue) with structural improvements (investment)
• Creating options for future changes by improving code structure
• Recognizing that uncertainty and volatility can increase the value of options

Understanding these economic principles helps developers make informed decisions about when and how much to invest in software design.

3. Coupling and Cohesion: Fundamental Principles of Software Design

"cost(software) ~= coupling"

Coupling and cohesion are fundamental principles that drive the cost and quality of software. Coupling refers to the interdependence between different elements of a system, while cohesion describes how well the elements within a module work together.

Key points:

• High coupling increases the cost of changes and maintenance
• Low cohesion makes code harder to understand and modify
• Reducing coupling and increasing cohesion are primary goals of software design
• Decoupling isn't free and involves trade-offs

Effective software design seeks to minimize coupling between modules while maximizing cohesion within modules. This approach leads to more flexible, maintainable, and less expensive software systems.

4. Reversible Structure Changes: The Power of Flexible Design

"What's the difference between a bad haircut and a bad tattoo? The bad haircut grows out, but the bad tattoo is forever."

Reversible structure changes are a key advantage of software design compared to many other engineering disciplines. Most software design decisions can be easily undone, which allows for more experimentation and iteration.

Benefits of reversible changes:

• Reduced risk in making design decisions
• Encourages experimentation and learning
• Allows for incremental improvements

When making design decisions, consider:

• Is this change easily reversible?
• If not, can we make it reversible through feature flags or other techniques?
• How can we minimize the impact of potentially irreversible changes?

By focusing on reversible changes, developers can make bolder design decisions and adapt more quickly to changing requirements.

5. Balancing Tidying and Behavior Changes

"Tidy first? Likely yes. Just enough. You're worth it."

Balancing tidying and behavior changes is crucial for effective software development. While tidying improves code structure and creates options for future changes, it's important not to get carried away and delay delivering value through behavior changes.

Guidelines for balancing:

• Tidy first when it will make the immediate behavior change easier or cheaper
• Tidy after when you've gained new insights from implementing a behavior change
• Tidy later when you have a backlog of improvements that don't directly impact current work
• Consider the economic trade-offs between immediate behavior changes and long-term structural improvements

Remember that the ultimate goal is to deliver value through working software. Tidying is a means to that end, not an end in itself.

6. Managing Tidying: Rhythm, Batch Sizes, and Chaining

"Tidyings are like potato chips. You eat one, and you'll want another."

Managing tidying effectively involves finding the right rhythm, batch sizes, and chaining of tidyings. This ensures that tidying remains productive and doesn't interfere with delivering value.

Key aspects of managing tidying:

• Rhythm: Aim for short bursts of tidying (minutes to hours) interspersed with behavior changes
• Batch sizes: Keep tidying batches small to reduce risk and improve review processes
• Chaining: Be aware of how one tidying can lead to another, but resist the urge to go down rabbit holes

Best practices:

• Separate tidying commits from behavior change commits
• Consider not requiring reviews for small, low-risk tidyings
• Be prepared to "get untangled" if tidying and behavior changes become mixed

Effective management of tidying helps maintain a healthy balance between improving code structure and delivering new features.

7. Software Design as an Exercise in Human Relationships

"Software design is preparation for change; change of behavior."

Software design as a human activity emphasizes the importance of relationships and communication in the development process. This perspective shifts the focus from purely technical considerations to the human aspects of software development.

Key relationships in software design:

• Individual developers with their code
• Developers within a team
• Development teams with business stakeholders

Implications:

• Design decisions affect how easily others can understand and modify the code
• Effective communication is crucial for making and explaining design choices
• Empathy and consideration for future developers (including your future self) should guide design decisions

By viewing software design through the lens of human relationships, developers can create more maintainable, collaborative, and valuable software systems.

Last updated: August 4, 2024