Add ability to ignore fields that match given regex pattern(s) (#199)

kong.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
+	"regexp"
 	"strings"
 )
 
@@ -48,10 +49,11 @@ type Kong struct {
 	Stdout io.Writer
 	Stderr io.Writer
 
-	bindings  bindings
-	loader    ConfigurationLoader
-	resolvers []Resolver
-	registry  *Registry
+	bindings          bindings
+	loader            ConfigurationLoader
+	resolvers         []Resolver
+	registry          *Registry
+	ignoreFieldsRegex []*regexp.Regexp
 
 	noDefaultHelp bool
 	usageOnError  usageOnError
@@ -73,13 +75,14 @@ type Kong struct {
 // See the README (https://github.com/alecthomas/kong) for usage instructions.
 func New(grammar interface{}, options ...Option) (*Kong, error) {
 	k := &Kong{
-		Exit:          os.Exit,
-		Stdout:        os.Stdout,
-		Stderr:        os.Stderr,
-		registry:      NewRegistry().RegisterDefaults(),
-		vars:          Vars{},
-		bindings:      bindings{},
-		helpFormatter: DefaultHelpValueFormatter,
+		Exit:              os.Exit,
+		Stdout:            os.Stdout,
+		Stderr:            os.Stderr,
+		registry:          NewRegistry().RegisterDefaults(),
+		vars:              Vars{},
+		bindings:          bindings{},
+		helpFormatter:     DefaultHelpValueFormatter,
+		ignoreFieldsRegex: make([]*regexp.Regexp, 0),
 	}
 
 	options = append(options, Bind(k))