golang inner func() 讓code變優雅變精巧

原始 for loop裡在進入時會進行許多的資料判別是否可以往下運行。程式看起來非常的冗長

func (a *ArbTriangular) stg() { var ( askDetph map[string]db.Order10Depth lastTicker map[string]db.LastTicker ) // ... // ... // ... for _, st := range *a.sTriangular { if st.isTrading { continue } if _, b := askDetph[st.a]; !b { continue } if _, b := askDetph[st.b]; !b { continue } if _, b := askDetph[st.c]; !b { continue } if _, b := lastTicker[st.a]; !b { continue } if _, b := lastTicker[st.b]; !b { continue } if _, b := lastTicker[st.c]; !b { continue } // ... // ... // ... } }

進行一次的重構，for loop 看起來好多了，但是冗長的if判別看起來還是不夠優雅

func (a *ArbTriangular) stg() { var ( askDetph map[string]db.Order10Depth bidDetph map[string]db.Order10Depth ) checkData := func(st SymboleTriangular) (b bool) { if st.isTrading { return } if _, b = askDetph[st.a]; !b { return } if _, b = askDetph[st.b]; !b { return } if _, b = askDetph[st.c]; !b { return } if _, b = bidDetph[st.a]; !b { return } if _, b = bidDetph[st.b]; !b { return } if _, b = bidDetph[st.c]; !b { return } b = true return } //... //... //... for _, st := range *a.sTriangular { if !checkData(st) { continue } //... //... //... } }

進行第二次的重構，這樣的成果優雅又精簡巧

func (a *ArbTriangular) stg() { var ( askDetph map[string]db.Order10Depth bidDetph map[string]db.Order10Depth existAsk = func(s string) (b bool) { _, b = askDetph[s] return } existBid = func(s string) (b bool) { _, b = bidDetph[s] return } checkData = func(st SymboleTriangular) bool { if st.isTrading || !existAsk(st.a) || !existAsk(st.b) || !existAsk(st.c) || !existBid(st.a) || !existBid(st.b) || !existBid(st.c) { return false } return true } ) //... //... //... for _, st := range *a.sTriangular { if !checkData(st) { continue } //... //... //... } }