This is a presentation about refactoring an open source project: https://github.com/aladine/EverOrg

1. REFACTORING A GOREFACTORING A GO
PROJECTPROJECT
DAN TRANDAN TRAN
Created: 2019-02-05 Tue 23:27
1

2. ABOUT THIS PROJECTABOUT THIS PROJECT
2 . 1

3. EVERORGEVERORG
Original repo:
Fork repo:
https://github.com/mgmart/EverOrg
https://github.com/aladine/EverOrg
2 . 2

4. HOW IT WORKSHOW IT WORKS
2 . 3

5. WHAT TO REFACTORWHAT TO REFACTOR
Statically checking Go source for errors and warning
Add benchmark test to improve performance
Add feature to split notebook to individual les
3 . 1

6. GO LINTER REPORTGO LINTER REPORT
4 . 1

7. GO REPORTGO REPORT
Link:
gofmt: linter
govet: examines Go source code and reports
suspicious constructs
gocyclo: check code complexity
golint: linting syntax code
ineffassign: detects ineffectual assignments in Go
code.
license
misspell
https://goreportcard.com
4 . 2

8. GOMETALINTERGOMETALINTER
go get gopkg.in/alecthomas/gometalinter.v1
gometalinter.v1 --disable=gocyclo --disable=vetshadow --disable=g
--disable=gotype --disable=errcheck --vendor --disable=golint
--disable=interfacer --json ./...
4 . 3

9. GOLANGCI LINTERGOLANGCI LINTER
go get -u github.com/golangci/golangci-lint/cmd/golangci-lint
GO111MODULE=on GOCACHE=on golangci-lint run

10. DEMO: GOLANGCI LINTERDEMO: GOLANGCI LINTER
4 . 5

11. STATIC ANALYSIS TOOLSSTATIC ANALYSIS TOOLS
4 . 6

12. GOFMTGOFMT
go fmt < gofmt < goimports
package main
import (
"fmt"
)
func main() {
s := []string{}
var m map[string]interface{}
s = append(s, "a")
s = append(s, "b")
for i, _ := range s {
fmt.Println(i)
m[s[i]] = i
}
}
4 . 7

13. A (maybe) better version
package main
import (
"fmt"
)
func main() {
var s []string
m := map[string]interface{}{}
s = append(s, "a")
s = append(s, "b")
for i := range s {
fmt.Println(i)
m[s[i]] = i
}
}
4 . 8

14. GORENAMEGORENAME
A precise, type-safe identi er renaming
4 . 9

15. ALIGNCHECKALIGNCHECK
4 . 10

16. // Note ...
type Note struct {
Title string `xml:"title"`
Content string `xml:"content"`
HasAttachments bool `xml:"has_attachments"`
Created string `xml:"created"`
IsDeleted bool `xml:"is_deleted"`
}
http://golang-sizeof.tips/
4 . 11

17. A better version
type Note struct {
Title string `xml:"title"`
Content string `xml:"content"`
Created string `xml:"created"`
HasAttachments bool `xml:"has_attachments"`
IsDeleted bool `xml:"is_deleted"`
}
4 . 12

18. GOCYCLOGOCYCLO
Calculates cyclomatic complexities of functions in Go
source code
The count +1 for each 'if', 'for', 'case', '&&' or '||'
It gives warning if total > 15
4 . 13

19. GO REPORT BEFORE & AFTERGO REPORT BEFORE & AFTER
4 . 14

20. BEFOREBEFORE

21. AFTERAFTER

22. TESTINGTESTING
5 . 1

23. TEST COVERAGETEST COVERAGE
5 . 2

24. go test -covermode=count -coverprofile=count.out
go tool cover -func=count.out
go tool cover -html=count.out
5 . 3

25. BENCHMARKBENCHMARK
5 . 4

26. go test -bench=. -benchtime=30s
goos: darwin
goarch: amd64
pkg: github.com/aladine/EverOrg
BenchmarkOrgFormatOriginal-12 100 44262624
BenchmarkOrgConcatStringBuffer-12 20000 213045
BenchmarkOrgConcatStringBuilder-12 30000 163609
PASS
ok github.com/aladine/EverOrg 180.019s
5 . 5

27. DEMO: GO BENCHMARKDEMO: GO BENCHMARK
5 . 6

28. OTHER POSSIBLE REFACTORINGOTHER POSSIBLE REFACTORING
Use interface more often, especially io.Reader and
io.Writer
Add more test to increase test coverage
5 . 7

29. Go Releaser
before:
hooks:
builds:
- env:
- CGO_ENABLED=0
- goos:
- darwin
- linux
- windows
- ignore:
- goos: darwin
goarch: 386
archive:
name_template: "{{ .ProjectName }}_{{ .Version }}_{{ .Os }}_{{
replacements:
darwin: Darwin
5 . 8

30. REFERENCEREFERENCE
Images:
http://golang-sizeof.tips/
https://dave.cheney.net/2015/10/09/padding-is-
hard
https://goreportcard.com
https://github.com/aladine/EverOrg
https://blog.golang.org/cover
https://github.com/alecthomas/gometalinter
https://github.com/golangci/golangci-lint
https://unsplash.com
6 . 1