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Generic way to import 'flag' flags into the 'pflag' system. #3342

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Jan 8, 2015
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4 changes: 2 additions & 2 deletions pkg/kubectl/cmd/cmd.go
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ import (
"github.com/GoogleCloudPlatform/kubernetes/pkg/client/clientcmd"
"github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl"
"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
"github.com/GoogleCloudPlatform/kubernetes/pkg/util"

"github.com/golang/glog"
"github.com/spf13/cobra"
Expand Down Expand Up @@ -100,12 +101,11 @@ Find more information at https://github.com/GoogleCloudPlatform/kubernetes.`,
Run: runHelp,
}

util.AddAllFlagsToPFlagSet(cmds.PersistentFlags())
f.ClientConfig = getClientConfig(cmds)

// Globally persistent flags across all subcommands.
// TODO Change flag names to consts to allow safer lookup from subcommands.
// TODO Add a verbose flag that turns on glog logging. Probably need a way
// to do that automatically for every subcommand.
cmds.PersistentFlags().Bool(FlagMatchBinaryVersion, false, "Require server version to match client version")
cmds.PersistentFlags().String("ns-path", os.Getenv("HOME")+"/.kubernetes_ns", "Path to the namespace info file that holds the namespace context to use for CLI requests.")
cmds.PersistentFlags().StringP("namespace", "n", "", "If present, the namespace scope for this CLI request.")
Expand Down
78 changes: 78 additions & 0 deletions pkg/util/plog_import.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,78 @@
/*
Copyright 2015 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package util

import (
"flag"
"reflect"
"strings"

"github.com/spf13/pflag"
)

// flagValueWrapper implements pflag.Value around a flag.Value. The main
// difference here is the addition of the Type method that returns a string
// name of the type. As this is generally unknown, we approximate that with
// reflection.
type flagValueWrapper struct {
inner flag.Value
flagType string
}

func wrapFlagValue(v flag.Value) pflag.Value {
// If the flag.Value happens to also be a pflag.Value, just use it directly.
if pv, ok := v.(pflag.Value); ok {
return pv
}

pv := &flagValueWrapper{
inner: v,
}
pv.flagType = reflect.TypeOf(v).Elem().Name()
pv.flagType = strings.TrimSuffix(pv.flagType, "Value")
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This is kinda broken for my quantity flag (https://github.com/GoogleCloudPlatform/kubernetes/blob/master/pkg/api/resource/quantity.go#L405)... not sure what to do about that

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Yeah - I'm not sure what to do here. Honestly, I'm not sure what anyone uses the "Type" method for in pflag.

If/When we switch everything over to pflag we can add a "Type" there.

Another option, if the flag.Value already is convertable to a pflag.Value type, we can just use it directly and not wrap. Not sure it is worth the effort though.

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Actually, here's a suggestion: start off with:

if pv, ok := v.(pflag.Value); ok {
  return pv
}

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done.

return pv
}

func (v *flagValueWrapper) String() string {
return v.inner.String()
}

func (v *flagValueWrapper) Set(s string) error {
return v.inner.Set(s)
}

func (v *flagValueWrapper) Type() string {
return v.flagType
}

// Imports a 'flag.Flag' into a 'pflag.FlagSet'. The "short" option is unset
// and the type is inferred using reflection.
func AddFlagToPFlagSet(f *flag.Flag, fs *pflag.FlagSet) {
fs.Var(wrapFlagValue(f.Value), f.Name, f.Usage)
}

// Adds all of the flags in a 'flag.FlagSet' package flags to a 'pflag.FlagSet'.
func AddFlagSetToPFlagSet(fsIn *flag.FlagSet, fsOut *pflag.FlagSet) {
fsIn.VisitAll(func(f *flag.Flag) {
AddFlagToPFlagSet(f, fsOut)
})
}

// Adds all of the top level 'flag' package flags to a 'pflag.FlagSet'.
func AddAllFlagsToPFlagSet(fs *pflag.FlagSet) {
AddFlagSetToPFlagSet(flag.CommandLine, fs)
}