Merge pull request #63432 from deads2k/cli-46-printerinterface

Automatic merge from submit-queue (batch tested with PRs 63421, 63432, 63333). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

 slim printer interface down to printing

The printer interface only needs to know how to print.  This reduces it's interface to scope it to printing.

@kubernetes/sig-cli-maintainers 
@soltysh @juanvallejo  you've been active in the area

/assign @juanvallejo 

```release-note
NONE
```

pkg/kubectl/cmd/get/get.go

@@ -53,10 +53,10 @@ import (
 
 // GetOptions contains the input to the get command.
 type GetOptions struct {
-	PrintFlags           *PrintFlags
+	PrintFlags             *PrintFlags
-	ToPrinter            func(*meta.RESTMapping, bool) (printers.ResourcePrinterFunc, error)
+	ToPrinter              func(*meta.RESTMapping, bool) (printers.ResourcePrinterFunc, error)
-	IsGeneric            bool
+	IsHumanReadablePrinter bool
-	PrintWithOpenAPICols bool
+	PrintWithOpenAPICols   bool
 
 	CmdParent string
 
@@ -216,13 +216,10 @@ func (o *GetOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []stri
 		o.ServerPrint = false
 	}
 
-	// obtain printer here in order to determine if we are
+	// human readable printers have special conversion rules, so we determine if we're using one.
-	// printing humanreadable or generic output.
+	if len(*o.PrintFlags.OutputFormat) == 0 || *o.PrintFlags.OutputFormat == "wide" {
-	printer, err := o.PrintFlags.ToPrinter()
+		o.IsHumanReadablePrinter = true
-	if err != nil {
-		return err
 	}
-	o.IsGeneric = printer.IsGeneric()
 
 	o.IncludeUninitialized = cmdutil.ShouldIncludeUninitialized(cmd, false)
 	o.PrintWithOpenAPICols = cmdutil.GetFlagBool(cmd, useOpenAPIPrintColumnFlagLabel)
@@ -318,7 +315,7 @@ func (o *GetOptions) Run(f cmdutil.Factory, cmd *cobra.Command, args []string) e
 		Latest().
 		Flatten().
 		TransformRequests(func(req *rest.Request) {
-			if o.ServerPrint && !o.IsGeneric && !o.Sort {
+			if o.ServerPrint && o.IsHumanReadablePrinter && !o.Sort {
 				group := metav1beta1.GroupName
 				version := metav1beta1.SchemeGroupVersion.Version
 
@@ -335,7 +332,7 @@ func (o *GetOptions) Run(f cmdutil.Factory, cmd *cobra.Command, args []string) e
 		return err
 	}
 
-	if o.IsGeneric {
+	if !o.IsHumanReadablePrinter {
 		return o.printGeneric(r)
 	}
 
@@ -544,7 +541,7 @@ func (o *GetOptions) watch(f cmdutil.Factory, cmd *cobra.Command, args []string)
 			objsToPrint = append(objsToPrint, obj)
 		}
 		for _, objToPrint := range objsToPrint {
-			if !o.IsGeneric {
+			if o.IsHumanReadablePrinter {
 				// printing always takes the internal version, but the watch event uses externals
 				internalGV := mapping.GroupVersionKind.GroupKind().WithVersion(runtime.APIVersionInternal).GroupVersion()
 				objToPrint = attemptToConvertToInternal(objToPrint, legacyscheme.Scheme, internalGV)

pkg/kubectl/sorter.go

@@ -44,10 +44,6 @@ type SortingPrinter struct {
 	Decoder   runtime.Decoder
 }
 
-func (s *SortingPrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 func (s *SortingPrinter) PrintObj(obj runtime.Object, out io.Writer) error {
 	if !meta.IsListType(obj) {
 		return s.Delegate.PrintObj(obj, out)
@@ -59,15 +55,6 @@ func (s *SortingPrinter) PrintObj(obj runtime.Object, out io.Writer) error {
 	return s.Delegate.PrintObj(obj, out)
 }
 
-// TODO: implement HandledResources()
-func (s *SortingPrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (s *SortingPrinter) IsGeneric() bool {
-	return s.Delegate.IsGeneric()
-}
-
 func (s *SortingPrinter) sortObj(obj runtime.Object) error {
 	objs, err := meta.ExtractList(obj)
 	if err != nil {

pkg/printers/customcolumn.go

@@ -150,10 +150,6 @@ type CustomColumnsPrinter struct {
 	lastType reflect.Type
 }
 
-func (s *CustomColumnsPrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 func (s *CustomColumnsPrinter) PrintObj(obj runtime.Object, out io.Writer) error {
 	if w, found := out.(*tabwriter.Writer); !found {
 		w = GetNewTabWriter(out)
@@ -236,11 +232,3 @@ func (s *CustomColumnsPrinter) printOneObject(obj runtime.Object, parsers []*jso
 	fmt.Fprintln(out, strings.Join(columns, "\t"))
 	return nil
 }
-
-func (s *CustomColumnsPrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (s *CustomColumnsPrinter) IsGeneric() bool {
-	return true
-}

pkg/printers/humanreadable.go

@@ -257,14 +257,6 @@ func (h *HumanReadablePrinter) HandledResources() []string {
 	return keys
 }
 
-func (h *HumanReadablePrinter) AfterPrint(output io.Writer, res string) error {
-	return nil
-}
-
-func (h *HumanReadablePrinter) IsGeneric() bool {
-	return false
-}
-
 func (h *HumanReadablePrinter) unknown(data []byte, w io.Writer) error {
 	_, err := fmt.Fprintf(w, "Unknown object: %s", string(data))
 	return err

pkg/printers/interface.go

@@ -28,12 +28,6 @@ import (
 type ResourcePrinter interface {
 	// Print receives a runtime object, formats it and prints it to a writer.
 	PrintObj(runtime.Object, io.Writer) error
-	HandledResources() []string
-	//Can be used to print out warning/clarifications if needed
-	//after all objects were printed
-	AfterPrint(io.Writer, string) error
-	// Identify if it is a generic printer
-	IsGeneric() bool
 }
 
 // ResourcePrinterFunc is a function that can print objects
@@ -44,19 +38,6 @@ func (fn ResourcePrinterFunc) PrintObj(obj runtime.Object, w io.Writer) error {
 	return fn(obj, w)
 }
 
-// TODO: implement HandledResources()
-func (fn ResourcePrinterFunc) HandledResources() []string {
-	return []string{}
-}
-
-func (fn ResourcePrinterFunc) AfterPrint(io.Writer, string) error {
-	return nil
-}
-
-func (fn ResourcePrinterFunc) IsGeneric() bool {
-	return true
-}
-
 type PrintOptions struct {
 	// supported Format types can be found in pkg/printers/printers.go
 	OutputFormatType     string

pkg/printers/internalversion/printers_test.go

@@ -268,7 +268,7 @@ func TestPrinter(t *testing.T) {
 		if err != nil {
 			t.Errorf("in %s, unexpected error: %#v", test.Name, err)
 		}
-		if printer.IsGeneric() && len(test.OutputVersions) > 0 {
+		if len(test.OutputVersions) > 0 {
 			printer = printers.NewVersionedPrinter(printer, legacyscheme.Scheme, legacyscheme.Scheme, test.OutputVersions...)
 		}
 		if err := printer.PrintObj(test.Input, buf); err != nil {

pkg/printers/json.go

@@ -31,10 +31,6 @@ import (
 type JSONPrinter struct {
 }
 
-func (p *JSONPrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 // PrintObj is an implementation of ResourcePrinter.PrintObj which simply writes the object to the Writer.
 func (p *JSONPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	switch obj := obj.(type) {
@@ -58,15 +54,6 @@ func (p *JSONPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	return err
 }
 
-// TODO: implement HandledResources()
-func (p *JSONPrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (p *JSONPrinter) IsGeneric() bool {
-	return true
-}
-
 // YAMLPrinter is an implementation of ResourcePrinter which outputs an object as YAML.
 // The input object is assumed to be in the internal version of an API and is converted
 // to the given version first.
@@ -75,10 +62,6 @@ type YAMLPrinter struct {
 	converter runtime.ObjectConvertor
 }
 
-func (p *YAMLPrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 // PrintObj prints the data as YAML.
 func (p *YAMLPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	switch obj := obj.(type) {
@@ -98,12 +81,3 @@ func (p *YAMLPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	_, err = fmt.Fprint(w, string(output))
 	return err
 }
-
-// TODO: implement HandledResources()
-func (p *YAMLPrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (p *YAMLPrinter) IsGeneric() bool {
-	return true
-}

pkg/printers/jsonpath.go

@@ -110,10 +110,6 @@ func NewJSONPathPrinter(tmpl string) (*JSONPathPrinter, error) {
 	return &JSONPathPrinter{tmpl, j}, nil
 }
 
-func (j *JSONPathPrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 // PrintObj formats the obj with the JSONPath Template.
 func (j *JSONPathPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	var queryObj interface{} = obj
@@ -150,12 +146,3 @@ func (j *JSONPathPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	}
 	return nil
 }
-
-// TODO: implement HandledResources()
-func (p *JSONPathPrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (p *JSONPathPrinter) IsGeneric() bool {
-	return true
-}

pkg/printers/name.go

@@ -42,10 +42,6 @@ type NamePrinter struct {
 	Typer    runtime.ObjectTyper
 }
 
-func (p *NamePrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 // PrintObj is an implementation of ResourcePrinter.PrintObj which decodes the object
 // and print "resource/name" pair. If the object is a List, print all items in it.
 func (p *NamePrinter) PrintObj(obj runtime.Object, w io.Writer) error {
@@ -123,12 +119,3 @@ func printObj(w io.Writer, name string, operation string, shortOutput bool, grou
 	fmt.Fprintf(w, "%s.%s/%s%s\n", strings.ToLower(groupKind.Kind), groupKind.Group, name, operation)
 	return nil
 }
-
-// TODO: implement HandledResources()
-func (p *NamePrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (p *NamePrinter) IsGeneric() bool {
-	return true
-}

pkg/printers/template.go

@@ -57,10 +57,6 @@ func (p *GoTemplatePrinter) AllowMissingKeys(allow bool) {
 	}
 }
 
-func (p *GoTemplatePrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 // PrintObj formats the obj with the Go Template.
 func (p *GoTemplatePrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	var data []byte
@@ -87,15 +83,6 @@ func (p *GoTemplatePrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	return nil
 }
 
-// TODO: implement HandledResources()
-func (p *GoTemplatePrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (p *GoTemplatePrinter) IsGeneric() bool {
-	return true
-}
-
 // safeExecute tries to execute the template, but catches panics and returns an error
 // should the template engine panic.
 func (p *GoTemplatePrinter) safeExecute(w io.Writer, obj interface{}) error {

pkg/printers/versioned.go

@@ -45,22 +45,12 @@ func NewVersionedPrinter(printer ResourcePrinter, converter runtime.ObjectConver
 	}
 }
 
-func (p *VersionedPrinter) AfterPrint(w io.Writer, res string) error {
-	return nil
-}
-
 // PrintObj implements ResourcePrinter
 func (p *VersionedPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	// if we're unstructured, no conversion necessary
 	if _, ok := obj.(*unstructured.Unstructured); ok {
 		return p.printer.PrintObj(obj, w)
 	}
-	// if we aren't a generic printer, we don't convert.  This means the printer must be aware of what it is getting.
-	// The default printers fall into this category.
-	// TODO eventually, all printers must be generic
-	if !p.IsGeneric() {
-		return p.printer.PrintObj(obj, w)
-	}
 
 	// if we're already external, no conversion necessary
 	gvks, _, err := p.typer.ObjectKinds(obj)
@@ -93,12 +83,3 @@ func (p *VersionedPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	}
 	return p.printer.PrintObj(converted, w)
 }
-
-// TODO: implement HandledResources()
-func (p *VersionedPrinter) HandledResources() []string {
-	return []string{}
-}
-
-func (p *VersionedPrinter) IsGeneric() bool {
-	return p.printer.IsGeneric()
-}