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![CleanCode-Avoidimplicitdependency
type Processor struct {
SomeData []string
}
func (p *Processor) Init() {
p.SomeData = []string{"foo", "bar"}
}
func (p *Processor) Step() {
element := p.SomeData[0]
// do something with element
}
Youhavetoknowthatyouhavetocall Init beforecalling Step ,otherwisetheprogram
willcrash.
19](https://image.slidesharecdn.com/softwareengineeringprinciples-221002112710-22c38088/85/Jaap-Groeneveld-Software-Engineering-Principles-19-320.jpg)
![CleanCode-Avoidimplicitdependency
func NewProcessor(someData []string) *Processor {
return &Processor{
SomeData: someData,
}
}
type Processor struct {
SomeData []string
}
func (p *Processor) Step() {
element := p.SomeData[0]
// do something with element
}
See http.Request vs http.NewRequest
20](https://image.slidesharecdn.com/softwareengineeringprinciples-221002112710-22c38088/85/Jaap-Groeneveld-Software-Engineering-Principles-20-320.jpg)
![[2015/2016] Software systems engineering PRINCIPLES](https://cdn.slidesharecdn.com/ss_thumbnails/01seprinciples-151104110430-lva1-app6891-thumbnail.jpg?width=640&height=640&fit=bounds)
Jaap Groeneveld - Software Engineering Principles
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- 9. CleanCode-Namingguidelines Example d := 12// elapsed time in days // vs elapsedTimeInDays := 12 9
- 10. CleanCode-Explanatoryvariables func doSomething() { deferStartTimer()() // ... } // vs func doSomething() { stopTimer := StartTimer() defer stopTimer() // ... } Yesitsonelinemore... 10
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- 15. Stepdown-Example package api func CreatePost(whttp.ResponseWriter, r *http.Request) { post, err := getPostFromRequest(r) if err != nil {...} err = validatePost(post) if err != nil { ... } err = savePost(post) if err != nil { ... } http.WriteHeader(201) } func getPostFromRequest(r *http.Request) (Post, error) { ... } func validatePost(post Post) error { ... } func savePost(post Post) error { ... } 15
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- 18. CleanCode-Dedicatedvaluetypesoverprimitivetype. func getUserData(userID string){} // vs type UserID string func getUserData(userID UserID) {} Impossibleto"accidentally"assignsomethingelse EasytofindwhereUserIDsareused(searchabilitythroughstaticanalysis) Preventspositionalproblemsinfunctions Allowsaddingfunctionstothetype see typed_primitives.go 18
- 19. CleanCode-Avoidimplicitdependency type Processor struct{ SomeData []string } func (p *Processor) Init() { p.SomeData = []string{"foo", "bar"} } func (p *Processor) Step() { element := p.SomeData[0] // do something with element } Youhavetoknowthatyouhavetocall Init beforecalling Step ,otherwisetheprogram willcrash. 19
- 20. CleanCode-Avoidimplicitdependency func NewProcessor(someData []string)*Processor { return &Processor{ SomeData: someData, } } type Processor struct { SomeData []string } func (p *Processor) Step() { element := p.SomeData[0] // do something with element } See http.Request vs http.NewRequest 20
- 21. CleanCode-Avoidimplicitdependency Anotherexample func GetFoo(w http.ResponseWriter,r *http.Request) { dataStore := r.Context().Value("FooDataStore").(FooDataStore) all := dataStore.All() _ = json.NewEncoder(w).Encode(all) } func main() { err := http.ListenAndServe(":8080", http.HandlerFunc(GetFoo)) if err != nil { log.Fatal(err) } } panic:interfaceisnil 21
- 22. CleanCode-Avoidimplicitdependency Basicallyifyouhaveto"know"somethingthatmightbeanimplicitdependency func GetFoo(dataStore FooDataStore)http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { all := dataStore.All() _ = json.NewEncoder(w).Encode(all) }) } func main() { dataStore = NewFooDataStore() err := http.ListenAndServe(":8080", GetFoo(dataStore)) if err != nil { log.Fatal(err) } } Weenforcecorrectusage 22
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- 31. DependencyinjectioninGo package cli type DataStoreinterface { GetData() model.Data } func Run(dataStore DataStore) {} package persistence type FileDataStore struct {} func (s *FileDataStore) GetData() model.Data package main func main() { dataStore := &persistence.FileDataStore{} cli.Run(dataStore) } 31
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