package template import ( "fmt" "regexp" "text/template" ) type ErrFail struct { msg string } func (err ErrFail) Error() string { return err.msg } var helperFuncs = template.FuncMap{ "fail": func(format string, args ...any) (any, error) { return nil, ErrFail{fmt.Sprintf(format, args...)} }, // Alias for https://pkg.go.dev/regexp#Compile. Allows usage of all methods of regexp.Regexp "regexp": func(expr string) (*regexp.Regexp, error) { return regexp.Compile(expr) }, }