3months has recently refreshed its library, getting rid of some (really) old books and buying a bunch of new ones. When we need books about specific technologies, we prefer to buy an eBook for the office kindle. Some books, though, deserve to be owned in physical form.

If you are going to buy a dead-wood version of a book, you really do want it to be a long-term investment. No cutting-edge technology books, no mediocre or unproven books, if you can help it. To that end, we ordered the following:

The Elements of Style - Strunk & White

Our jobs involve a lot of written communication. S&W is considered one of the best guides to writing well.

Design Patterns: Elements of Reusable Object-Oriented Software - Gamma, Helm, Johnson, Vlissides

One of the standard books. Everyone knows they should have read it, few have. It can be a dry read, but the material is worth the investment. There has been a lot of competition in the office for this book!

Practical Object-Oriented Design in Ruby: An Agile Primer - Sandi Metz

This book is deceptively slim and basic, but the core concepts it imparts about OO design are great. Another book in high demand around here.

Working Effectively with Legacy Code - Michael Feathers

I've being going through this book and I've found it packed with practical, pragmatic advice for dealing with the horror of untested, hard-to-maintain code. I highly recommend this book.

Code Complete: A Practical Handbook of Software Construction - Steve McConnell

The heaviest of our books, Code Complete covers an enormous range of topics and comes highly recommended. No-one has yet been brave enough to crack it open, but we'll get there.

Growing Object-Oriented Software, Guided by Tests - Steve Freeman

Covers TDD and emergent OO design in a practical way. Another book that hasn't yet had too many hands on it, but that's bound to change soon!

3months already has a decent library of real and electronic books, but I'm quite pleased that we've added this set. One of the hardest things to pick up is the craft of programming, and a well-written book will add a lot of tools to a developer's toolbox.

We've already started compiling a list for the next refresh. Let us know if you have any recommendations!

Decimals are an important tool if you want reliable values to use in e.g. financial software. Ruby provides a BigDecimal class that you can use for this sort of thing. The normal way is to initialise it in the traditional manner:

BigDecimal.new("0.5")

But the most concise way to do it is with good, old-fashioned type coercion:

"0.5".to_d

This little titbit is surely not news to many Rails developers, but it certainly has proved handy for me.

Render or redirect must be called exactly once in a controller action. This makes sense as each action represents a single server response.

Normally your controllers will be simple enough that this is trivial to verify. Occasionally, though, you may need to have a relatively complex selection of renders or redirect commands such that you can't guarantee a render has been performed or not by the time you get to the end of the method.

Often this is a sign that you are asking your controller to do too much. Sometimes, however, knowing this can be really handy.

The performed? method returns true if a render has already been called for the request.

Easy.