Learning go for perl programmers
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The document discusses differences between Perl and Go for Perl programmers. It covers Go topics like goroutines (threads), channels (queues), formatting code with gofmt, defining structs instead of hashes/objects, using slices instead of arrays, maps instead of hashes, error handling, importing packages instead of using Perl modules, writing tests with godoc instead of perldoc, and getting code with go get instead of cpanminus. It also provides Golang web resources for learning more.
![Array => Slice
var tallActors []string
tallActors = append(tallActors, “Dolph Lundgren”)
tallActors[0] = “Richard Kiel”
tallActors[1] = “Chevy Chase” // error: index out of range
tallActors = append(tallActors, “Vince Vaughn”)
tallActorsCopy := make([]string, len(tallActors))
copy(tallActorsCopy, tallActors)](https://image.slidesharecdn.com/learninggoforperlprogrammers-160609063600/85/Learning-go-for-perl-programmers-7-320.jpg)
![Array => Array
// not used nearly as much as slices
var tenIntegers [10]int
fiveIntegers := [5]int{1,2,3,4,5}
lastThreeIntegers := fiveIntegers[2:] // outputs 3,4,5
firstTwoIntegers := fiveIntegers[:2] // outputs 1,2](https://image.slidesharecdn.com/learninggoforperlprogrammers-160609063600/85/Learning-go-for-perl-programmers-8-320.jpg)
![Hash => Map
countries := make(map[string]int)
countries[“Canada”] = 1
countries[“US”] = 2
canadaId = countries[“Canada”] // 1
delete(countries, “US”)
countries := map[string]int{“Canada”: 1, “US”: 2}
countryId, exists := countries[“Atlantis”] // exists == nil](https://image.slidesharecdn.com/learninggoforperlprogrammers-160609063600/85/Learning-go-for-perl-programmers-9-320.jpg)
![Loops
for i:= 0; i < 10; i++ {
fmt.Printf(“We’re going to 11”, i+1)
}
for i, actor := range []string{“Van Dam”, “Liam Neeson”} {
fmt.Printf(“#%d is %v”, i, actor) // %v default format
}
for _, actor := ... // _ ignores the loop iterator value](https://image.slidesharecdn.com/learninggoforperlprogrammers-160609063600/85/Learning-go-for-perl-programmers-10-320.jpg)
![$@ => err
bytesRead, err := w.Write([]byte{“data written to client”})
if err != nil {
log.WithField("err", err).Error("write to client failed")
}
var err error // built in error type
err.Error() // format error as a string](https://image.slidesharecdn.com/learninggoforperlprogrammers-160609063600/85/Learning-go-for-perl-programmers-11-320.jpg)
![sub foo => func foo (bar string, boo int)
func httpEndpoint(world string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r
*http.Request) {
bytesRead, _ := w.Write([]byte(
fmt.Sprintf(“Hello %v!”, world)))
return
}
}](https://image.slidesharecdn.com/learninggoforperlprogrammers-160609063600/85/Learning-go-for-perl-programmers-13-320.jpg)
Learning go for perl programmers
- 1. Learning Go for Perl Programmers Fred Moyer SF Perl Mongers, 06082016
- 2. The Go Programming Language Developed at Google circa 2007 Goroutines (threads) Channels (queues) One way to format code (gofmt)
- 3. Hello SF.pm! package main import "fmt" func main() { fmt.Println("Hello, サンフランシスコのPerlモンガー") }
- 4. Hash || Object => Struct type Person struct { id int // lowercase fields are not exported email string // note no commas after variable type Name string HeightCentimeters float32 // camelCase convention IsAlive bool // true or false, defaults to false }
- 5. Hash || Object => Struct var famousActor = Person{ id: 1, email: "[email protected]", Name: "Jeff Goldblum", // no single quotes HeightCentimeters: 193.5, IsAlive: true, }
- 6. Hash || Object => Struct // we all knew this day would come // perhaps in Independence Day: Resurgence? // use the dot notation to make it happen famousActor.IsAlive = false
- 7. Array => Slice var tallActors []string tallActors = append(tallActors, “Dolph Lundgren”) tallActors[0] = “Richard Kiel” tallActors[1] = “Chevy Chase” // error: index out of range tallActors = append(tallActors, “Vince Vaughn”) tallActorsCopy := make([]string, len(tallActors)) copy(tallActorsCopy, tallActors)
- 8. Array => Array // not used nearly as much as slices var tenIntegers [10]int fiveIntegers := [5]int{1,2,3,4,5} lastThreeIntegers := fiveIntegers[2:] // outputs 3,4,5 firstTwoIntegers := fiveIntegers[:2] // outputs 1,2
- 9. Hash => Map countries := make(map[string]int) countries[“Canada”] = 1 countries[“US”] = 2 canadaId = countries[“Canada”] // 1 delete(countries, “US”) countries := map[string]int{“Canada”: 1, “US”: 2} countryId, exists := countries[“Atlantis”] // exists == nil
- 10. Loops for i:= 0; i < 10; i++ { fmt.Printf(“We’re going to 11”, i+1) } for i, actor := range []string{“Van Dam”, “Liam Neeson”} { fmt.Printf(“#%d is %v”, i, actor) // %v default format } for _, actor := ... // _ ignores the loop iterator value
- 11. $@ => err bytesRead, err := w.Write([]byte{“data written to client”}) if err != nil { log.WithField("err", err).Error("write to client failed") } var err error // built in error type err.Error() // format error as a string
- 12. use => import import ( "database/sql" "encoding/json" "flag" "fmt" )
- 13. sub foo => func foo (bar string, boo int) func httpEndpoint(world string) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { bytesRead, _ := w.Write([]byte( fmt.Sprintf(“Hello %v!”, world))) return } }
- 14. t/test.t => main_test.go main.go # file containing your code, ‘go run main.go’ main_test.go # unit test for main.go go test # runs main_test.go, executes all tests func TestSomething(t *testing.T) { // do some stuff if err != nil { t.Errorf("test failed %v", err) } }
- 15. perldoc => godoc $ godoc fmt use 'godoc cmd/fmt' for documentation on the fmt command PACKAGE DOCUMENTATION package fmt import "fmt" ...
- 16. perldoc => godoc $ godoc fmt Sprintf use 'godoc cmd/fmt' for documentation on the fmt command func Sprintf(format string, a ...interface{}) string Sprintf formats according to a format specifier and returns the resulting string.
- 18. cpanminus => go get go get github.com/quipo/statsd $ ls gocode/src/github.com/quipo/statsd/ LICENSE bufferedclient_test.go event README.md client.go interface.go bufferedclient.go client_test.go noopclient.go
- 19. PERL5LIB => GOPATH $ echo $GOPATH /Users/phred/gocode $ ls gocode/ bin pkg src $ ls gocode/src/ github.com glenda golang.org
- 20. ? => go build $ pwd ~/gocode/src/myorg/myapp $ ls main.go main_test.go $ go build; ls main.go main_test.go myapp ./myapp # binary executable you can relocate to same arch
- 21. queues => channels c := make(chan string) // queue for string data type hello := “Hello SF.pm” c <- hello // ... fmt.Println(<-c) // prints “Hello.SF.pm” bufferedChannel := make(chan string, 2) // buffers 2 strings // channels are first class citizens of Go
- 22. threads => goroutines hello := “Hello SF.pm” go myFunc(hello) func myFunc(myString string) { fmt.Println(myString) } // spawns an asynchronous thread which executes a function // goroutines are first class citizens of Go
- 23. Tour of Golang web places https://golang.org/ https://tour.golang.org/welcome/1 https://golang.org/pkg/ https://groups.google.com/forum/#!forum/golang-nuts
- 24. Questions?