Refactoring - Agile Tech Conference 2016

Understanding 
Refactoring
Bryan Beecham 
@BillyGarnet 
bryan@industriallogic.com
Writing Healthy Code

@BillyGarnet
Is software designed to be simple and elegant more valuable 
than software that is complex and hard to maintain?

@BillyGarnet
~9600 line vb class named frm2

@BillyGarnet
“Simplicity is the only thing that really scales.”
–Joshua Kerievsky

@BillyGarnet
Modern Agile
Make People Awesome 
Make Safety a Prerequisite 
Experiment and Learn Rapidly 
Deliver Value Continuously

@BillyGarnet
Refactoring
Improving the design of existing code

@BillyGarnet
“Refactoring is the process of changing a software system
in such a way that it does not alter the external behaviour
of the code yet improves its internal structure.”
–Martin Fowler

@BillyGarnet
It must work.
It must be understandable.
It must be updatable.
Needs of Software
What should software do?

Reasons to extract a function
✤ To reuse it (the only reason some consider).
✤ To name it’s operation.
✤ To make it testable.
✤ To get it out of your way so you can see the code that called it more clearly.

@BillyGarnet
Remove the Clutter.
Remove the Complexity.
Remove the Cleverness.
Three Cs

@BillyGarnet
Duplication
Duplication
Duplication
Three Ds

@BillyGarnet
Ring of Fire
Johnny Cash

@BillyGarnet
➤ Love is a burnin' thing,
➤ And it makes a fiery ring
➤ Bound by wild desire
➤ I fell into a ring of fire.
➤ I fell into a burnin' ring of
fire
➤ I went down, down, down
➤ And the flames went higher,
➤ And it burns, burns, burns,
➤ The ring of fire, the ring of
fire.
➤ I fell into a burnin' ring of
fire
➤ The ring of fire, the ring of
fire.
➤ The taste of love is sweet
➤ When hearts like ours meet.
➤ I fell for you like a child
➤ Oh, but the fire went wild.
➤ I fell into a burnin' ring of fire
➤ The ring of fire, the ring of fire.
➤ I fell into a burnin' ring of fire
➤ I went down, down, down,
➤ The ring of fire, the ring of fire
➤ The ring of fire

@BillyGarnet
Love is a burnin' thing,
And it makes a fiery ring
Bound by wild desire
I fell into a ring of fire.
I fell into a burnin' ring of fire
I went down, down, down
And the flames went higher,
And it burns, burns, burns,
The ring of fire, the ring of
fire.
The ring of fire, the ring of fire.
The taste of love is sweet
When hearts like ours meet.
I fell for you like a child
Oh, but the fire went wild.
I went down, down, down,
The ring of fire, the ring of fire
The ring of fire

@BillyGarnet
fire.
fire.
The ring of fire

@BillyGarnet
 
(CHORUS)
fire.
fire.
The ring of fire

@BillyGarnet
 
(CHORUS)
CHORUS
CHORUS
CHORUS
fire.
fire
The ring of fire

@BillyGarnet
(CHORUS)
The ring of ﬁre
CHORUS
CHORUS

@BillyGarnet
Wow!
That’s much easier to read

@BillyGarnet
How many people have been on a project where
the requirements didn’t change?

@BillyGarnet
Quotes
From some people I like…

@BillyGarnet
“It seems that perfection is attained
not when there is nothing more to add,
but when there is nothing more to remove.”
–Antoine de Saint Exupéry

@BillyGarnet
“Refactoring ought to be invisible.  
It should be part of every task, and not a task on its own.”
~Tim Ottinger

@BillyGarnet
“It (refactoring) is the cheapest and safest way to read code. It is also the only way
to safely change untestable code so that you can then start wrapping it in tests.”
~Arlo Belshee

@BillyGarnet
“ Getting an app to work is the app-titude test for a programmer. 
There is a lot more to programming than just getting your app to work”
~James Grenning

@BillyGarnet
“Refactoring can be done in smaller steps than you think it can,
never breaking the program.”
~Ron Jeffries

@BillyGarnet
“Relentless refactoring is the single best thing you  
can do to ﬁx and avoid technical debt”
~Declan Whelan

@BillyGarnet
“I refactor for one reason: to reduce volatility in the marginal cost of features.”
~J.B. Rainsberger

@BillyGarnet
“Refactoring is like breathing. You should do it all of the
time without giving it much thought.”
~Jeff ‘Cheezy’ Morgan

@BillyGarnet
“We refactor to embrace change.”
~Bryan Beecham

@BillyGarnet
“You have two options, you can refactor, or you can build a big ball of mud.”
~Chet Hendrickson

@BillyGarnet
“For each desired change, make the change easy (warning: this may be hard),  
then make the easy change.”
~Kent Beck

@BillyGarnet
“If you’re a little better each day, next year you’ll be great. 
If you’re a little worse each day, next year you’ll be horrible.”
~Llewellyn Falco

@BillyGarnet
“Imagine how good a bowler you could be if you could adjust the direction of the
ball once it's left your hands. Refactoring is what does that for us in writing code.”
~Woody Zuill

@BillyGarnet
“Business is well served by continuous refactoring, yet the practice of refactoring
must co-exist harmoniously with business priorities.”
~Joshua Kerievsky

@BillyGarnet
“Refactoring, above all else, is a tool for managing risk.”
~Amitai Schlair

@BillyGarnet
“To me, refactoring is the most pleasant part of programming. 
I ﬁnd it meditative and soothing, to change my code and my design
until it can be grasped almost instantly.”
~Mike ‘GeePaw’ Hill

@BillyGarnet
“Rename class is the most powerful refactoring.”
~Michael Feathers

@BillyGarnet
“The way to arrest entropy in software is to refactor it.”
~Joseph Yoder

@BillyGarnet
“So if you want to go fast, if you want to get done quickly,  
if you want your code to be easy to write, make it easy to read.”
~Uncle Bob Martin

@BillyGarnet
HumanRefactoring
Get up! Get on up!

@BillyGarnet
Inside Refactoring
Prepare
Improve
Clean

Prepare
✤ Prepare has also been referred to as nesting, making room, prefactoring or
rough-in. We make small changes to the code so the improvement can take
place.

Improve
✤ Improve is when we make an improvement to the code without changing
its external behaviour.

Clean
✤ Clean is when we remove code we have made unnecessary and put the
code back in a state to start something new.
✤ At this point we are done refactoring and can run tests, and, assuming they
pass, integrate this refactoring.

Make a sandwich
✤ Get out all the things you need
✤ Assemble the sandwich
✤ Put everything away

Working Effectively with Legacy Code
✤ 1. Identify the code you want to extract and comment it out.
✤ 2. Think of a new name for a method and create it as an empty method.
✤ 3. Place a call to the new method in the old method.
✤ 4. Copy the code you want to extract into the new method.
✤ 5. Lean on the Compiler to ﬁnd out what parameters you’ll have to pass and what values you’ll have to
return.
✤ 6. Adjust the method declaration to accommodate the parameters and return value (if any).
✤ 7. Run your tests.
✤ 8. Delete your commented out code.

Prepare
✤ 1. Identify the code you want to extract and comment it out.
✤ 2. Think of a new name for a method and create it as an empty method.
✤ 3. Place a call to the new method in the old method.

Improve
✤ 4. Copy the code you want to extract into the new method.
✤ 5. Lean on the Compiler to ﬁnd out what parameters you’ll have to pass
and what values you’ll have to return.
✤ 6. Adjust the method declaration to accommodate the parameters and
return value (if any).
✤ 7. Run your tests.

Clean
✤ 8. Delete your commented out code.

@BillyGarnet
Inside Refactoring
Example

@BillyGarnet
def convert(arabic):
numeral = ""
for i in range(0, arabic):
numeral += "I"
return numeral

@BillyGarnet
numeral = ""
current_number = arabic
for i in range(0, current_number):
if current_number >= 10:
numeral += "X"
current_number -= 10
for i in range(0, current_number):
numeral += "I"
return numeral

@BillyGarnet
numeral = ""
if arabic >= 10:
numeral += "X"
arabic -= 10
if arabic >= 1:
numeral += "I"
arabic -= 1
return numeral

@BillyGarnet
numeral = ""
arabic_value = 10
roman_value = "X"
if arabic >= arabic_value:
numeral += roman_value
arabic -= arabic_value
arabic_value = 1
roman_value = "I"
if arabic >= arabic_value:
numeral += roman_value
arabic -= arabic_value
return numeral

@BillyGarnet
numeral = ""
arabic_digits = [10, 1]
roman_digits = ["X", "I"]
for i in range(0, len(arabic_digits)):
while arabic >= arabic_digits[i]:
numeral += roman_digits[i]
arabic -= arabic_digits[i]
# arabic_digits = 1
# roman_digits = "I"
# for i in range(0, arabic):
# if arabic >= arabic_digits:
# numeral += roman_digits
# arabic -= arabic_digits
return numeral

@BillyGarnet
numeral = ""
arabic_digits = [10, 1]
roman_digits = ["X", "I"]
for i in range(0, len(arabic_digits)):
while arabic >= arabic_digits[i]:
numeral += roman_digits[i]
arabic -= arabic_digits[i]
return numeral

@BillyGarnet
arabic_digits = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1] 
roman_digits = ['M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I']

Bryan Beecham 
@BillyGarnet 
bryan@industriallogic.com
Questions
and
Answers

Clarity
if (x){ return true } else if (!x) { return false }
if (x) return true 
return false
if (x){ 
return true
} else if (!x) {  
return false
}
return x

Clutter
//
// This is cool
// I saw it on a blog and thought if we changed our code
// it could work. Call me if you need more explanation
//
//

@BillyGarnet
Books
✤ Refactoring - Martin Fowler
✤ Working Effectively with Legacy Code - Michael Feathers
✤ Refactoring to Patterns - Joshua Kerievsky
✤ Refactoring Workbook - Bill Wake
✤ Healthy Code - Getting Started with Refactoring - Bryan Beecham

Refactoring - Agile Tech Conference 2016

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