Brian Candler schrieb am Sonntag, 19. September 2021 um 20:46:45 UTC+2:
>
> I'm not sure how useful that is though, especially because "return" inside
> that anonymous function will return from that anonymous function, not the
> outer function.
> https://go2goplay.golang.org/p/h6ZRnqM5cRx
>
Yes, this is a problem. Then after calling myerror.As in the next line you
still to check whether err was not nil and if it was handled, and if so, do
a return.
> Unfortunately, in order to use this proposed version, you still need to
pre-declare the variables for each type
Yes, that is tedious.
To solve the problem that a return from the error block would only jump out
of the As function, but not out of the surrounding function, either some
special new language construct needs to be added for handling errors (any
kind of function would always bear the problem that a return from the
function is a local return and not a non-local as a return from an if
clause) or things just stay with:
_, err := os.Open("non-existing")
if pe, ok := errors.As[*os.PathError](err); ok {
fmt.Printf("Path Error: %v", pe)
} else if en, ok := errors.As[syscall.Errno](err); ok {
fmt.Printf("errno %[1]d: %[1]s", en)
}
Not too bad, but still a bit painful considering how often you have to
write this kind of code for all the errors that need to be handled
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