go - 如何优雅地使 slice 追加安全

Question

slice := []int{10, 20, 30, 40, 50,60}

newSlice := slice[2:4:5]



fmt.Printf("old slice is %d \n", slice)
fmt.Printf("new slice is %d \n", newSlice)

newSlice = append(newSlice,70)

fmt.Printf("old slice is %d \n", slice)
fmt.Printf("new slice is %d \n", newSlice)

newSlice = append(newSlice,80)

fmt.Printf("old slice is %d \n", slice)
fmt.Printf("new slice is %d \n", newSlice)

输出将是

old slice is [10 20 30 40 50 60] 
new slice is [30 40] 
old slice is [10 20 30 40 70 60] 
new slice is [30 40 70] 
old slice is [10 20 30 40 70 60] 
new slice is [30 40 70 80] 

追加有不同的行为。我知道导致追加有不同行为的原因。因为新分片容量大于length时新旧共享数组，但是append 80，容量不够大，所以创建了一个新数组。所以检查容量将避免附加有不同的行为或者我可以定义新的 slice newSlice := slice[2:4:4]

有什么优雅的解决方案吗？因为每次append之前check有点难看，而且在某些情况下希望新老一直共享slice。如何让它优雅地发生？

Answer 1

这是一个非常好的随机 slice 资源:https://github.com/golang/go/wiki/SliceTricks

在这种情况下，我建议先创建一个新 slice ，然后每次都添加元素，如下所示:

slice := []int{10, 20, 30, 40, 50, 60}

newSlice := make([]int, 0)
newSlice = append(newSlice, slice[2:4:5]...)

fmt.Printf("old slice is %d \n", slice)
fmt.Printf("new slice is %d \n", newSlice)

newSlice = append(newSlice, 70)

fmt.Printf("old slice is %d \n", slice)
fmt.Printf("new slice is %d \n", newSlice)

newSlice = append(newSlice, 80)

fmt.Printf("old slice is %d \n", slice)
fmt.Printf("new slice is %d \n", newSlice)

结果是:

old slice is [10 20 30 40 50 60] 
new slice is [30 40] 
old slice is [10 20 30 40 50 60] 
new slice is [30 40 70] 
old slice is [10 20 30 40 50 60] 
new slice is [30 40 70 80]