英文:
no-op/explicitly do nothing in go
问题
我有一个类型方法，可以改变类型的字段。它不接受任何参数，也不返回任何值。该方法的主要部分是一个switch块。我想要能够在switch块中使用一个空操作来“短路”退出。在将其重构为类型方法之前，我可能会直接从函数中返回，但那样不行。删除该case将破坏方法的逻辑——default情况会改变状态，如果匹配到该情况，我不想这样做。我需要类似于Python中的pass的功能。
代码：
func (parser *Parser) endSectionName() {
state := parser.State
buffer := parser.buffer
results := parser.results
switch {
case state.HasFlag(IN_ESCAPED):
// ???
case !inSection(state):
return state, NotInSectionError
case !state.HasFlag(IN_SECTION_NAME):
state.Reset()
return state, errors.New("Parsing error: Not in section name")
default:
state.RemoveFlag(IN_SECTION_NAME)
s := buffer.String()
results[s] = new(Section)
buffer.Reset()
return state, nil
}
}
请注意，我只翻译了代码部分，其他内容不包括在内。
英文:
I have a type method that mutates the type's fields. It takes no arguments and returns nothing. The bulk of the method is a switch block. I want to be able to "short-circuit" out of the switch block with a no-op. Before I refactored it into a type method, I would've just returned out of the function, but that's out. Removing the case would break the logic of the method--the default case mutates state, which I don't want to do if this case is matched. I need the equivalent of Python's pass, basically.
Code:
func (parser *Parser) endSectionName () {
state = parser.State
buffer = parser.buffer
results = parser.results
switch {
case state.HasFlag(IN_ESCAPED) {
// ???
}
case !inSection(state) {
return state, NotInSectionError
}
case !state.HasFlag(IN_SECTION_NAME) {
state.Reset()
return state, errors.New("Parsing error: Not in section name")
}
default {
state.RemoveFlag(IN_SECTION_NAME)
s := buffer.String()
results展开收缩 = new(Section)
buffer.Reset()
return state, nil
}
}
}
答案1
得分: 31
与其他语言不同，在Go语言中，控制流在每个case语句处中断，除非使用fallthrough语句明确要求控制流进入下一个case。
而且，在case之后不需要必须有语句（可以为空）。看下面的例子：
i := 3
switch i {
case 3:
case 0:
fmt.Println("Hello, playground")
}
即使i==3并且在case 3之后没有语句，它也不会打印任何内容。
与此类似的是：
i := 3
switch {
case i == 3:
case i == 0:
fmt.Println("Hello, playground")
}
在Go Playground上尝试一下。
英文:
Unlike in other languages, in Go the control flow breaks at each case of a switch statement, control doesn't flow into the next case unless it is explicitly "asked" for with the fallthrough statement.
And also a statement is not required after the case (it can be empty). See this example:
i := 3
switch i {
case 3:
case 0:
fmt.Println("Hello, playground")
}
It will print nothing even though i==3 and there is no statement after case 3.
Same as this:
i := 3
switch {
case i == 3:
case i == 0:
fmt.Println("Hello, playground")
}
Try it on the Go Playground.
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