Use errors.As() #3542
Use errors.As() #3542
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| @@ -134,7 +135,11 @@ func (c *DSLContext) Record(err *Error) { | |||
| if c.Errors == nil { | |||
| c.Errors = MultiError{err} | |||
| } else { | |||
| c.Errors = append(c.Errors.(MultiError), err) | |||
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I wonder if in this case this is necessary? The type of the Errors field is controlled by Goa and guaranteed to be MultiError, see https://github.com/goadesign/goa/blob/v3/eval/context.go#L16
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Yes, but it can be a different error type in the Go type system. For clarity, how about changing DSLContext.Errors to MultiError?
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Yes making that change makes sense
eval/eval.go
Outdated
| @@ -71,14 +72,20 @@ func Execute(fn func(), def Expression) bool { | |||
| } | |||
| var startCount int | |||
| if Context.Errors != nil { | |||
| startCount = len(Context.Errors.(MultiError)) | |||
| var e MultiError | |||
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Same here, not sure this is needed.
| } | ||
| Context.Stack = append(Context.Stack, def) | ||
| fn() | ||
| Context.Stack = Context.Stack[:len(Context.Stack)-1] | ||
| var endCount int | ||
| if Context.Errors != nil { | ||
| endCount = len(Context.Errors.(MultiError)) |
| e, ok := err.(*ServiceError) | ||
| if !ok { | ||
| var e *ServiceError | ||
| if !errors.As(err, &e) { |
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This should be As. The Go Blog says
https://go.dev/blog/go1.13-errorse
In the simplest case, the errors.Is function behaves like a comparison to a sentinel error, and the errors.As function behaves like a type assertion
I added test for asError(). It fails if you replace As with Is.
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Makes sense, thanks for the clarification!
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