Go is your friend - Reppucci

ROME April 11-12th 2014
Go is your friend
Gianfranco Reppucci

Lead Developer at Qurami
giefferre

ROME April 11-12th 2014 - Gianfranco Reppucci
About me

Evolution
As developers,

we’ve changed a lot since a decade ago

Evolution
• Monolithic, 100% custom code

• Super-complete, MVC frameworks
with tons of built-in features

• Simple, bootstrapping frameworks 
w/ dependency managers

Context
• There is a lot of different languages
available to developers

• Some of them are pretty easy, some
others have great performances

• We can find frameworks and plugins for
each of them

The big dilemma
I’m starting a new project.

Which technology do you think I should use?

There’s no right choice
As developers:

• A great idea can be built with
(perhaps) any language

• Pros and cons are everywhere

• You’ll pay a certain price for whatever
advantages you could have

There’s no right choice
As entrepreneurs:

• When choosing a specific technology, 
you’ll probably need to justify the
decision to yourself, your partners and
investors

• Decisions would be based on
company’s vision

Start using 
something modern
Go is an open source programming language 
that makes it easy to build simple, 
reliable and efﬁcient software.
quote from golang.org

What Go is:
• Open source BSD licensed project

• Language specification

• Runtime components 
(garbage collector, scheduler, etc)

• Two different compilers (gc or gccgo)

• Standard libraries

• Documentation

History
• Developed at Google in 2007 as an
experiment

• Publicly announced in 2009

• Integrated in App Engine in 2011

Who is using Go?

A modern C
Go sits somewhere between C and Python.
!
It has the static type checking and bit-
twiddling powers of C, yet much of the speed
of development and conciseness of Python.
quote from Graham King

Absolutely genuine
• No class inheritance

• No method or operator overloading

• No circular dependencies among packages

• No generic programming

• No assertions

• No pointer arithmetic

Performance driven
Built-in concurrency primitives:

• light-weight threads, called goroutines

• channels

• select statements

I mean, seriously

Does God exist?
• If you have doubts or issues when
styling your Go code, you can use
gofmt

• gofmt’s aim is to format Go files,
returning a valid and “beautified”
version of the code

A little bit of code

Object Oriented Go

A type declaration
! type Name struct {!
! ! First string!
! ! Middle string!
! ! Last string!
! }

A method declaration
! func (n Name) String() string {!
! ! return fmt.Sprintf(!
! ! ! “%s %c. %s”,!
! ! ! n.First,!
! ! ! n.Middle[0],!
! ! ! n.Last,!
! ! )!
! }

Instancing a Name
! aName := Name{“John”, “Go”, “White”}!
!
! fmt.Println(aName.String())

Goroutines

Given the yell function
func yell(word string, seconds int) {!
! time.Sleep(time.Duration(seconds) * time.Second)!
! fmt.Println(word)!
}

Guess what’s the output
func main() {!
! go yell(“2014”, 5)!
! go yell(“Codemotion”, 1)!
! go yell(“Roma”, 4)!
! time.Sleep(10 * time.Second)!
}

Channels

Channels
• Implement parallelism and
synchronization

• Channels can be of any type of data
structure, even custom structs

• Can be buffered or unbuffered

An example
c := make(chan int)!
!
go func() {!
! list.Sort()!
! c <- 1!
}()!
!
doSomethingForAWhile()!
<-c

Select statement

Select
The select statement is like a switch, but 
it selects over channel operations and 
chooses exactly one of them

An example
ticker := time.NewTicker(250 * time.Millisecond)!
boom := time.After(1 * time.Second)!
!
for {!
! select {!
! ! case <- ticker.C:!
! ! ! fmt.Println(“tick”)!
! ! case <- boom:!
! ! ! fmt.Println(“BOOM!”)!
! ! ! return!
! }!
}

Start writing your 
Go code now
Open your browser and point it to

http://tour.golang.org

for a quick tour, or

http://play.golang.org

to test your own snippets online

Why should I use Go?
• Syntax and environments are similar to
dynamic languages

• Simple language specification

• Powerful and lightweight

Why should I use Go?
• Full development environment 
(doc, dependencies, formatter, tests)

• Static compilation 
with NO dependencies binary output

• Multi environment build

So, what’s Go about?

Composition
• Go is Object Oriented, 
BUT not in the usual way!

• Simple data models, simple interfaces

Concurrency
• Easily readable concurrency primitives

Gophers

Join us tonight
GOLANGIT
Meetup

18:40 - 19.40

Thank you!
Gianfranco Reppucci
giefferre

References
• The gopher images were created by Renee
French and they are Creative Commons
Attribution 3.0 licensed

• What technology should my startup use? by
Matt Aimonetti

• Go after four months by Graham King

• Golang on Google’s App Engine

References
• List of organizations that use Go

• The gopher look, a photo by Ken Conley

• How we went from 30 servers to 2 by Travis
Reeder

• Go after 2 years in production by Travis
Reeder

• Computer Language Benchmarks Game

References
• Go at Google

• Docker and Go: why did we decide to write
docker in Go?

Go is your friend - Reppucci

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