Proposal: Make Go support exception handling #39498
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Relevant FAQ entry: https://golang.org/doc/faq#exceptions |
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You are adding as many keywords as in the old check/handle proposal, but with a more limited functionality. In fact, all your examples can be written using only check: // Exception handling mode
func SomeFunctionWithException(src, dst string) (string, error) {
r := check os.Open(src) // throw implicitly
defer r.Close()
w, err := os.Create(dst)
if err != nil {
check fmt.Errorf("look!!! : %v", err) // rethrow explicitly
}
defer w.Close()
// ...
}
// Go error check mode
func SomeFunction() error {
// SomeFunctionWithException is defined above
_, err := SomeFunctionWithException("foo", "bar")
if err != nil {
return fmt.Errorf("look!!! : %v", err)
}
}
// Invoke "trhowable funcion"
func SomeFunction() error {
// SomeFunctionWithException is defined above
check SomeFunctionWithException("foo", "bar")
}
// Example
func CopyFileWithThrow(src, dst string) error {
r := check os.Open(src)
defer r.Close()
w := check os.Create(dst)
defer w.Close()
check io.Copy(w, r)
}
func RebuildError() error {
err := CopyFileWithThrow("foo", "bar")
if err != nil {
return fmt.Errorf("look!!! : %v", err)
}
}Calling it exception handling does not help. |
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For what it's worth, I would say that Go actually has exception handling, via |
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@ianlancetaylor Thanks for your clarifying. In fact, my proposal just like exception, but it is not. It is a way to make us coding without checking error explicitly |
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We know there are many proposals about Go error checking design problem. I learn a lot from these proposals. I have an idea. I think that we maybe make Go has two error handling modes. So, we need a way to convert Go functions between two modes.
We use two new keywords
throwandcheck. If a function's last result value has anerrortype. We cancheckthis function. If this function returns a no-nil error, it throws this error.For running a throwable function in a Go normal function, we use
handlekeyword to handle it, at the same time convert it a normal function.Or invoke a throwable function in a throwable function
Example:
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