英文:
Golang casting a multiple return value to match named result parameter
问题
假设我想定义一个带有命名结果参数的函数，其中一个参数是一个字符串。这个函数内部调用另一个函数，该函数返回该字符串的字节表示。
有没有一种方法可以在不使用临时变量的情况下进行类型转换？
func main() {
out, _ := bar("Example")
fmt.Println(out)
}
func foo(s string) ([]byte, error) {
return []byte(s), nil
}
func bar(in string) (out string, err error) {
// 是否有一种方法可以将结果赋值给out，
// 在同一行中将值转换为字符串，
// 而不是使用临时变量？
tmp, err := foo(in)
if err != nil {
return "", err
}
return string(tmp), nil
}
这个想法是，如果可能的话，我可以将代码缩短为：
func bar(in string) (out string, err error) {
// 假设有一种方法可以将out转换为字符串
out, err := foo(in)
return
}
这样是否有意义？
英文:
Let's assume I want to define a function with named result parameters, one of which is a string. This function internally calls another function, that returns a bytes representation of such string.
Is there a way to cast the result without using a temporary variable?
func main() {
out, _ := bar("Example")
fmt.Println(out)
}
func foo(s string) ([]byte, error) {
return []byte(s), nil
}
func bar(in string) (out string, err error) {
// is there a way to assign the result to out
// casting the value to string in the same line
// istead of using the tmp variable?
tmp, err := foo(in)
if err != nil {
return "", err
}
return string(tmp), nil
}
The idea is that, if that's possible, I could potentially shorten the code to
func bar(in string) (out string, err error) {
// assuming there is a way to cast out to string
out, err := foo(in)
return
}
Does it make sense?
答案1
得分: 10
从函数中返回多个值时，没有办法进行类型转换。但这并不意味着你不能简化你的代码。如果你不关心错误，那么只需在内联返回中进行变量转换即可。
英文:
There is no way to cast in a multiple return from a function. That doesn't mean you can't shorten your code though. http://play.golang.org/p/bf4D71_rZF If you don't care about the error then just cast the variable in your inline return
答案2
得分: 2
1行代码不会有太大的区别，但是在整个函数中保留一个tmp变量是一个问题。临时变量应该是临时的，显然。为此，您可以在一个新的作用域中声明tmp。
var s string;
{
tmp, err := foo(in)
s = string(tmp)
}
//tmp在这里不再存在。
//其他代码不会受到无用的tmp变量的干扰。
我可能只是太蠢了，因为我刚接触Go，我从C中学到了这个技巧，结果在Go中也适用。
英文:
1 line of code won't make a huge difference but having a tmp variable actually sticking around for the entire function is a problem. Temporary variables should be temporary, obviously. For that, you can declare tmp in a new scope.
var s string;
{
tmp, err := foo(in)
s = string(tmp)
}
//tmp no longer exists here.
//Other code is not disturbed by a useless tmp variable.
I may be just being stupid here as I am new to Go, I learnt this trick from C, turns out it works for Go as well.
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