This repo is for use in the discussions at golang/go#29934 only.
It shows hot to use go generate to make typed functions for the proposed Last(error, func(error) bool) error.
It uses genny.
type MyError struct {/* */}
func (*MyError) Error() string {/* */}
//go:generate genny ...
// and this produces (in a different file but same package):
func LastMyError(err error) *MyError {/* */}
// note the return type is not error by *MyErrorIt has 3 packages:
- xerrros: represents the proposed changed to the standard library
- _gennyrics: the files I use alongside genny to generate the types code
- exampleusage: a main, where you can validate everything works as expected
The output of running the main is:
*MyErrorPtr to MyErrorPtr: pointer implements error - I support foo!
*MyErrorPtr to Foorer: pointer implements error - I support foo!
MyError to MyError: value implements error - I support bar!
MyError to Barer: value implements error - I support bar!
MyError{*MyErrorPtr} to MyErrorPtr: pointer implements error - I support foo!
MyError{*MyErrorPtr} to MyError: value implements error - I support bar!
MyError{*MyErrorPtr} to Foorer: pointer implements error - I support foo!
MyError{*MyErrorPtr} to Barer: value implements error - I support bar!
*MyErrorPtr{MyError} to MyErrorPtr: pointer implements error - I support foo!
*MyErrorPtr{MyError} to MyError: value implements error - I support bar!
*MyErrorPtr{MyError} to Foorer: pointer implements error - I support foo!
*MyErrorPtr{MyError} to Barer: value implements error - I support bar!