英文:
Create a map of string to List
问题
我想创建一个从字符串到container/list.List实例的映射。这样做的方式正确吗？
package main
import (
"fmt"
"container/list"
)
func main() {
x := make(map[string]*list.List)
x["key"] = list.New()
x["key"].PushBack("value")
fmt.Println(x["key"].Front().Value)
}
英文:
I'd like to create a map of string to container/list.List instances. Is this the correct way to go about it?
package main
import (
"fmt"
"container/list"
)
func main() {
x := make(map[string]*list.List)
x["key"] = list.New()
x["key"].PushBack("value")
fmt.Println(x["key"].Front().Value)
}
答案1
得分: 191
每当我想使用List时，我发现切片是正确的选择，例如
package main
import "fmt"
func main() {
x := make(map[string][]string)
x["key"] = append(x["key"], "value")
x["key"] = append(x["key"], "value1")
fmt.Println(x["key"][0])
fmt.Println(x["key"][1])
}
英文:
Whenever I've wanted to use a List I've found that a slice was the right choice, eg
package main
import "fmt"
func main() {
x := make(map[string][]string)
x["key"] = append(x["key"], "value")
x["key"] = append(x["key"], "value1")
fmt.Println(x["key"][0])
fmt.Println(x["key"][1])
}
答案2
得分: 43
我最喜欢的声明字符串到字符串切片的映射的语法是：
mapOfSlices := map[string][]string{
"first": {},
"second": []string{"one", "two", "three", "four", "five"},
"third": []string{"quarter", "half"},
}
英文:
My favorite syntax for declaring a map of string to slice of string:
mapOfSlices := map[string][]string{
"first": {},
"second": []string{"one", "two", "three", "four", "five"},
"third": []string{"quarter", "half"},
}
答案3
得分: 8
你写的代码在技术上没有问题，但是你应该定义自己的类型，围绕map[string]*list.List，以避免一些陷阱，比如试图在空指针上调用.Front()方法。或者将其定义为map[string]list.List以避免这种情况。list.List只是一对指针和一个长度值；在你的map中使用list.List指针只是在空列表的情况下添加了一个空指针的额外情况。无论哪种情况，你都应该为这种用例定义一个新的结构体。
我倾向于这样写：
http://play.golang.org/p/yCTYdGVa5G
英文:
there's nothing technically incorrect about what you've written, but you should define your own type around map[string]*list.List to avoid some pitfalls, like trying to call the .Front() method on a nil pointer. Or make it a map[string]list.List to avoid that situation. A list.List is just a pair of pointers and a length value; using a list.List pointer in your map just adds the extra case of a nil pointer on top of the case of an empty list. In either situation, you should define a new struct for this use case.
I would be inclined to write it like this:
http://play.golang.org/p/yCTYdGVa5G
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