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Software Horticulture
and other terrible analogies

What is software engineering?
Coding

Coding
Designing

Coding
Designing
Communicating

Important

Recent
Important

Unique
Recent
Important

We use analogies

We use analogies
to link to familiar things

We use analogies
to build intuition

We use analogies
to build intuition
to frame methodologies

But analogies are imperfect

But analogies are imperfect
and taking them too far can lead to
incorrect or incomplete conclusions

Build a structure or machine from raw materials

Structures need to stay standing

Structures need to stay standing
Machines need to work

Heavy on planning and design

Breaking is permanent and catastrophic

Breaking is permanent and catastrophic
Requirements are clearly set in advance

It’s for “very serious people.”

Requirements
Design
Execution
Verification
Production

This is nothing like how software is built today.

Too slow and inflexible

Too slow and inflexible
Can we tolerate failure of any sort?

“It is important to say right up front that quality
isn't everything, and acknowledging it isn't
some sort of moral failing. Value is what you
are trying to produce, and quality is only one
aspect of it, intermixed with cost, features, and
other factors.”

other factors.”
Mark Zuckerberg

other factors.”
John Carmack

Business demands
Outputs

What is software economics?
Find the right match between

Demand for business logic PMs

Demand for business logic
Supply of business logic
PMs
Devs

yes

Trade offs

Trade offs
Time

Trade offs
Time
Quality
Scope

What is software horticulture?

“If you think about it, building software is more
like gardening than building.”

some guy I know

Walter Hilton
Software Architect at Advertising.
com

Babysitting - safety in both compile and run time

Landscaping - encouraging flexibility

Landscaping - encouraging flexibility
Linguistics - communication of intent

What is software babysitting?
What are the two biggest
impediments to programming?

Fear of being wrong

Fear of being wrong
Being wrong

Static analysis is a huge safety net

Type safety, immutability

Type safety, immutability
Use it and use it wisely

val a = 20
val b = if (a == None) {
30
} else {
40
}

var a = 1; var b = 0;
if (a = 2) {
b += 1
} else {
b += 2
}

1. Never use vars

1. Never use vars
2. Never use AnyVal or Any.

1. Never use vars
3. Never do Option.get

1. Never use vars
3. Never do Option.get
4. Be as functional as possible

Testing is incredibly important
A sieve that catches runtime errors

Unit testing is for finicky business logic
Functional testing is for sanity checks

Singletons
Can trap state across application shutdowns

Singletons
Can trap state across application shutdowns
Use cake pattern for service unit tests
Use reloadable registry for controller
functional tests

What is software landscaping?
Design for composition

Design for composition
Would rather have Legos than a BMW

traits

traits
type classes

traits
type classes
first class functions

trait CanBark; trait HasPaws
class Dog extends CanBark with HasPaws
class Dog extends Canine
class Canine extends Mammal

trait UserComponent
trait QuestionComponent
object Registry
extends UserComponent
with QuestionComponent

trait Barkable[A]
implicit dogIsBarkable = new Barkable[Dog]
def seesBurglar[A](animal: A)(implicit b:
Barkable[A])

case class MyDTO(a: Int, b: String)
object MyDTO {
implicit val format: Format[MyDTO] =
Json.format[MyDTO]
}

def withAttack[A](animal: A)(attackF: A =>
Int): Int
withAttack(myDog) { dog =>
dog.attackPoints
}

myList.map(_ + 1)
Action { implicit request =>
Ok(request.body)
}

What is software linguistics?
Scala and most modern languages are not
designed to communicate with computers

Scala and most modern languages are not
designed to communicate with computers
They are designed to communicate with
humans!

Scala is a huge language.

Limit your use of weird paradigms.

Limit your use of weird paradigms.
If it is truly useful, teach it to your team

Questions to ask:

Questions to ask:
1. What syntax style to use? Dot vs. operator
method calls?

Questions to ask:
method calls?
2. What semantic style to use? Should use
for comprehensions?

Questions to ask:
method calls?
2. What semantic style to use? Should use
for comprehensions?
3. What structures to use? Cake pattern?
Actors?

Building software is a steady but constantly
changing endeavour to meet product
requirements.
Maintaining a codebase is a constant
process of grooming, never a complete
restructuring.

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Software Horticulture

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