Friday, 31 January 2014

London Code Dojo 30

Monday was London Code Dojo 30 and this time we were back in Barbican with the lovely people at valtech


The kata for the evening was based upon Fibonacci numbers... but with a twist! The problem was centred around Fibonaccimal Numbers (link) which use the Fibonacci numbers as a base for representing numbers. So taking 1, 2,3,5 and 8 as a base, we can represent 9 as 10001 or 01101. As you can see, some numbers can have multiple representations and this added to the complexity of the problem. For the majority of the evening I paired with Rob and I found it really valuable getting his insight into the problem! The code we produced for the night can be found here:


Nothing beats a good plan

More so then anything else, I came to appreciate the value of having a solid plan. Having a high level design which everyone agrees will solve the problem is incredibly important. Test driving code doesn't magically produce well designed algorithms.


Decompose complexity into simple functions

Functional concepts supplement object oriented coding in a fantastically seamless way. When dealing with collections or calculations it is surprising how  higher order functions like map and reduce translate to how you naturally think about the problems.

For instance, to produce all the Fibonaccimal representations of a number, you can use a two step process:
  1. Find all unique ways to express that number as a sum of different Fibonacci numbers 
    • For example: 3 is [3] and [2+1]
  2. Translate each way into the corresponding Fibonaccimal 
    • [3] is 100 and [2+1] is 011
These steps are both mapping a number to a list of lists, then each list to a String. This is reflected in the code below:
return sumsCalculator.fibonacciSumsFor(number) // Step 1
                             .map(toStringCalculator::fibonacciSumToString); // Step 2

Suddenly I've decomposed an abstract problem into two concrete functions which I understand and can test drive!

Perhaps this is the crux behind solving all problems. Reduce the complexity until the solution is series of simple steps. Needless to say, making things simple is not simple... But there in lies the rub :)

Monday, 20 January 2014

Skimmer's Guide - Head First Design Patterns - Introduction

“Our goal was to make the book weigh less than the person reading it... Our focus is on the core patterns that matter...”


I've recently started reading this book along with a few others in the LJC Book Club. As we read the book, I will be producing a series of Skimmer's Guide posts for each significant section of the book. Introduction to Design Patterns, the next section, is here. If you are interested, please join the discussion on our Google+ community


We start our reading of Head First Design Patterns with a gentle and enlightening introduction to the Head First world. Their approach is really intriguing and it is refreshing how much they are vested in helping the reader learn. Everything is to the point and we are immediately told who this book is and isn't for. Our goal in reading this book is stately clearly: learning that design patters are all about reusing experience and creating flexible code.

Despite the daunting size of this book (it is very heavy), the writing style and format makes it very easy and enjoyable to read. If you have experience with Head First books in the past, the introduction could be skipped although I highly recommend giving it a quick skim in the least.


Taster - Table of contents
Surprisingly enough, the novel table of contents work really well as a taster for things to come. Much like the rest of the book, the entertaining writing style brings the book to life :)


Tricking your brain into retaining knowledge
One of the very first concepts covered in the book, this is the art of learning how to best learn. Absolute must read as the techniques covered are applicable to learning in all walks fo life.


Beginning to read this book has been a wonderful foray into the Head First world and has whetted my appetite for more. Looking forward to sinking my teeth into the world of design patterns in the next part :D