Go中的2D切片类型转换

Question

I was constrained to define a particular type for []string because I implemented a custom yaml parser for the strSlice type.

Now I need to cast []strSlice back into [][]string but the go compiler 1.7.1 reject it as an error.

type strSlice []string
var x1 []strSlice
var x2 [][]string
...
x2 = [][]string(x1)

How can I perform the cast operation ?

Answer 1

You're using a named type of a string slice. You need to convert each entry in x1 back to a []string first:

type strSlice []string
var x1 []strSlice
var x2 [][]string
...
for _, s := range x1 {
    x2 = append(x2, []string(s))
}

https://play.golang.org/p/5iJT2Hsv1R

Unfortunately, there's no way to do this in one shot, because each of the indexes in x1 are a strSlice type, and need to be converted to a []string type to be stored in x2. Go doesn't let you do this in a single operation because the developers didn't want to hide O(n) operations in syntactical sugar.