Ruby Programming Idioms and Patterns

This is a (potential) book about idioms and patterns in Ruby.

Inspirations

I've given several talks about patterns and idioms, especially in Ruby. That has inspired me to collect more of them in a book form.

In a way, this is a clean-room reimplementation of Kent Beck's Smalltalk Best Practice Patterns. That's definitely the biggest inspiration. But I'd also like to incorporate patterns introduced several other books:

• Practical Object-Oriented Design in Ruby by Sandi Metz
• 99 Bottles of OOP by Sandi Metz and Katrina Owen
• Confident Ruby by Avdi Grimm
• Exceptional Ruby by Avdi Grimm

Patterns versus Idioms

Unfortunately, there's no clear distinction between an idiom and a pattern. While we tend to think of patterns as larger architectural features, there are also "patterns in the small"; Smalltalk Best Practice Patterns contains many examples.

An idiom is defined as a "recurring construct" or a "characteristic mode of expression". A pattern is defined as a "general, reusable solution". Given those definitions, it seems like an idiom is more of an expressive choice, and you might have particular idioms that you prefer to use over others. A pattern is something that is less of a stylistic choice; anyone would likely always choose the same one in a given situation.

Perhaps we can make a distinction between patterns that we have to think about, and idioms that have just become second nature. One canonical example of this is that in assembly langauge, a subrouting call is a pattern. But in higher-level languages, we no longer thing of that as a pattern; it's just a part of the language.

Format

For each pattern and idiom:

• Name
• When to use (contexts)
• How to use
• Examples
• Contra-indications
• Caveats