Provide flexible error formatting patterns?

[lordvidex]

Currently errors are formatted in a fixed way i.e.

err := B().Code(codes.Internal).Msg("some internal error").Err()
fmt.Println(err) // "internal: some internal error"

Users might want to provide a different formatting for the error messages. More importantly, wrapped errors are separated by a newline token \n and this can be restricting.

Temporary proposal

Currently, my idea is to provide some singleton config that should be set ONLY once, preferrably at the start of a program to specify the user's error formatting preferences.

For Example:

package errs
var prefs struct {
// separates code, op, msg
msgSeparator string // ": "
// separates wrapped errors
errSeparator string  // "\n"
}

func init() {
 prefs = defaultPrefs
}

func SetPreferences(o ...PrefOpts) {
...
}

... and can be used like:

package main 

func main() {
 errs.SetPreferences(
  WithMsgSeparator(", "),
  WithErrSeparator(func(depth int) { 
    "\n" + strings.Repeat("\t", depth)
   }),
   )
   
   // start work ...
}

Sidenote

No one has requested this feature yet, and this error format is the best for my usecases. Till I find a dynamic error API that won't hurt performance so much, I'll leave this issue open.