英文:
Get line number on which function returned
问题
从调用范围返回的函数是否可能获取行号？
示例：
func callee() error {
if cond {
return errors.New("whoops!")
}
return nil
}
func caller() {
// 是否可能在此处检索到callee返回的行号？
callee()
}
我认为这是不可能的，因为它应该已经从堆栈中移除了，但也许它仍然被缓存在某个地方？
使用案例是我有一个HTTP处理程序，我想记录返回错误的行号和文件名，而不必在代码中添加大量的代码。
英文:
Is it possible to get the line number on which a function returned from the calling scope?
Example:
func callee() error {
if cond {
return errors.New("whoops!")
}
return nil
}
func caller() {
// Possible to retrieve the line number of callee return here?
callee()
}
I assume that's not possible, since it should be already removed from the stack, but maybe it's still cached somewhere?
The use case is that I have a HTTP handler and I'd like to log the line and filename on which the error was returned, without having to litter the code.
答案1
得分: 7
AFAIK，不可能自动获取执行最后一个返回的行。
但是，通过一个小的辅助函数可以实现：
package main
import (
"fmt"
"runtime"
)
func here(s string, args ...interface{}) error {
_, fname, fline, _ := runtime.Caller(1)
h := fmt.Sprintf("%s:%d: ", fname, fline)
return fmt.Errorf(h+s, args...)
}
func foo(i int) error {
if i == 2 {
return here("无法处理 %d", i) // line 16
}
if i%3 == 0 {
return here("也无法处理 %d", i) // line 20
}
return nil
}
func main() {
fmt.Println(foo(2))
fmt.Println(foo(3))
fmt.Println(foo(4))
}
输出：
/tmpfs/gosandbox-92c2a0f2_32bdf9d9_3c7d2a0a_80ba8510_f68d9721/prog.go:16: 无法处理 2
/tmpfs/gosandbox-92c2a0f2_32bdf9d9_3c7d2a0a_80ba8510_f68d9721/prog.go:20: 也无法处理 3
<nil>
英文:
AFAIK, it is not possible to automatically acquire the line where the last return was executed.
However, with a small helper one can have:
package main
import (
"fmt"
"runtime"
)
func here(s string, args ...interface{}) error {
_, fname, fline, _ := runtime.Caller(1)
h := fmt.Sprintf("%s:%d: ", fname, fline)
return fmt.Errorf(h+s, args...)
}
func foo(i int) error {
if i == 2 {
return here("cannot handle %d", i) // line 16
}
if i%3 == 0 {
return here("also cannot handle %d", i) // line 20
}
return nil
}
func main() {
fmt.Println(foo(2))
fmt.Println(foo(3))
fmt.Println(foo(4))
}
Output:
/tmpfs/gosandbox-92c2a0f2_32bdf9d9_3c7d2a0a_80ba8510_f68d9721/prog.go:16: cannot handle 2
/tmpfs/gosandbox-92c2a0f2_32bdf9d9_3c7d2a0a_80ba8510_f68d9721/prog.go:20: also cannot handle 3
<nil>
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