英文:
Checking Dictionary Key Existence in Golang on right side of boolean condition
问题
我有一个包含地图的数组，在golang中，我正在遍历列表，并需要检查当前迭代中的键是否存在于列表中的下一个地图中，我知道检查元素是否存在于地图中的常规方法是这样做：
if _, ok := m[key]; ok {
...
}
但是有没有一种方法可以这样做？
if index < len(arr)-1 && (_, ok := arr[index+1][key]; ok) {
...
}
其中短路计算可以起作用，并且代码保持在一行中？
英文:
I have an array of maps in golang, I'm iterating over the list and need to check if a key from the current iteration exists in the next map in the list, I know the normal way to check if an element exists in a map is to do:
if _, ok := m[key]; ok {
...
}
but is there a way to do this?
if index < len(arr)-1 && (_, ok := arr[index+1][key]; ok) {
...
}
where short-circuiting would work and the code remains in one line?
答案1
得分: 2
据我所知，没有一种方法可以在一行中完成这个操作。
> Go语言中没有 ?: 的原因是，语言设计者发现该操作经常被用于创建难以理解的复杂表达式。if-else形式虽然更长，但无疑更清晰。一种语言只需要一种条件控制流构造。
而且，Go语言的一条格言是清晰胜于巧妙。
所以不要费力去做这个。就像这样写：
if index < len(arr)-1 {
if _, ok := arr[index+1][key]; ok {
//...
}
}
关于你遍历列表的问题，也许这样写更好：
// 假设arr至少有1个元素
for index := range arr[0 : len(arr)-1] {
if _, ok := arr[index+1][key]; ok {
//...
}
}
英文:
AFAIK, there is no way to do it in one line.
Hey, Go even does not have the ?: operator:
> The reason ?: is absent from Go is that the language's designers had seen the operation used too often to create impenetrably complex expressions. The if-else form, although longer, is unquestionably clearer. A language needs only one conditional control flow construct.
And one of Go's proverbs is Clear is better than clever.
So don't struggle with it. Just write it like this:
if index < len(arr)-1 {
if _, ok := arr[index+1][key]; ok {
//...
}
}
Regarding you're iterating over the list, maybe it's better to write it like this:
// assumes arr has at least 1 items
for index := range arr[0 : len(arr)-1] {
if _, ok := arr[index+1][key]; ok {
//...
}
}
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