英文:
Go believes variables inside conditional statements are unused?
问题
我有一个情况，如果某个变量未能分配成功，我会在条件语句中进行分配，但是Go似乎认为这个变量未被使用。
for index, value := range group.Values {
timestamp, err := time.Parse(time.RFC3339, value.Timestamp)
if err != nil {
strings.ReplaceAll(value.Timestamp, "+0000", "")
timestamp, err := time.Parse(time.RFC3339, value.Timestamp)
if err != nil {
log.Printf("Error parsing timestamp for point %s: (%s) %v", value.Context+"_"+value.ID, value.Timestamp, err)
continue
}
}
event := new(SplunkEvent)
event.Time = timestamp.Unix()
Go认为条件语句内的变量timestamp未被使用。为什么会这样？我明明在条件之后直接使用了它。
英文:
I have a situation where if something fails to assign a variable I instead assign it within a conditional statement however Go seems to think this variable is unused.
for index, value := range group.Values {
timestamp, err := time.Parse(time.RFC3339, value.Timestamp)
if err != nil {
strings.ReplaceAll(value.Timestamp, "+0000", "")
timestamp, err := time.Parse(time.RFC3339, value.Timestamp)
if err != nil {
log.Printf("Error parsing timestamp for point %s: (%s) %v", value.Context+"_"+value.ID, value.Timestamp, err)
continue
}
}
event := new(SplunkEvent)
event.Time = timestamp.Unix()
Go believes the variable timestamp inside the conditional statement is unused. Why is that? I have clearly used it directly after the condition.
答案1
得分: 1
嵌套的（内部的）timestamp声明遮蔽了外部的声明，因此外部的声明从未被设置。因此，由于内部值从未被使用，编译错误是有效的。
要修复这个问题，将:=声明的赋值操作符替换为=，以便重新使用外部作用域的timestamp（和err）值：
timestamp, err = time.Parse(time.RFC3339, value.Timestamp)
英文:
The nested (inner) timestamp declaration shadows the outer one - so the outer one is never set. So since the inner value is never used, the compilation error is valid.
To fix, replace := declared assignment operator with = to (re)use the outer scope's timestamp (and err) values:
timestamp, err = time.Parse(time.RFC3339, value.Timestamp)
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