refactor dehub binary's flags a bit

---
type: change
message: |-
  refactor dehub binary's flags a bit

  * Make flag outputting a bit prettier, omitting the flag section in both the
    usage header and the body if that sub-command has no flags set.

  * Use a different pattern for opening up the repo, since not all sub-commands
    will want to do so.
change_hash: AK10DRu7LBGpLHRHrQ7TMqgkofz1n1DwK16sg6tOGSq8
credentials:
- type: pgp_signature
  pub_key_id: 95C46FA6A41148AC
  body: 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
  account: mediocregopher

cmd/dehub/cmd_commit.go

@@ -15,7 +15,9 @@ func cmdCommit(ctx context.Context, cmd *dcmd.Cmd) {
 	flag := cmd.FlagSet()
 	accountID := flag.String("account-id", "", "Account to accredit commit with")
 
-	repo := ctxRepo(ctx)
+	var repo repo
+	repo.initFlags(flag)
+
 	accreditAndCommit := func(commit dehub.Commit) error {
 
 		cfg, err := repo.LoadConfig()
@@ -61,6 +63,10 @@ func cmdCommit(ctx context.Context, cmd *dcmd.Cmd) {
 			return nil, errors.New("-account-id is required")
 		}
 
+		if err := repo.openRepo(); err != nil {
+			return nil, err
+		}
+
 		var err error
 		if hasStaged, err = repo.HasStagedChanges(); err != nil {
 			return nil, fmt.Errorf("determining if any changes have been staged: %w", err)
@@ -177,6 +183,9 @@ func cmdCombine(ctx context.Context, cmd *dcmd.Cmd) {
 	startRev := flag.String("start", "", "Revision of the starting commit to combine")
 	endRev := flag.String("end", "", "Revision of the ending commit to combine")
 
+	var repo repo
+	repo.initFlags(flag)
+
 	cmd.Run(func() (context.Context, error) {
 		if *onto == "" ||
 			*startRev == "" ||
@@ -184,7 +193,10 @@ func cmdCombine(ctx context.Context, cmd *dcmd.Cmd) {
 			return nil, errors.New("-onto, -start, and -end are required")
 		}
 
-		repo := ctxRepo(ctx)
+		if err := repo.openRepo(); err != nil {
+			return nil, err
+		}
+
 		commits, err := repo.GetGitRevisionRange(
 			plumbing.Revision(*startRev),
 			plumbing.Revision(*endRev),

cmd/dehub/cmd_hook.go

@@ -18,13 +18,17 @@ func cmdHook(ctx context.Context, cmd *dcmd.Cmd) {
 	flag := cmd.FlagSet()
 	preRcv := flag.Bool("pre-receive", false, "Use dehub as a server-side pre-receive hook")
 
-	cmd.Run(func() (context.Context, error) {
+	var repo repo
+	repo.initFlags(flag)
 
+	cmd.Run(func() (context.Context, error) {
 		if !*preRcv {
 			return nil, errors.New("must set the hook type")
 		}
 
-		repo := ctxRepo(ctx)
+		if err := repo.openRepo(); err != nil {
+			return nil, err
+		}
 
 		br := bufio.NewReader(os.Stdin)
 		for {

cmd/dehub/cmd_util.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"dehub.dev/src/dehub.git"
+)
+
+type repo struct {
+	bare bool
+
+	*dehub.Repo
+}
+
+func (r *repo) initFlags(flag *flag.FlagSet) {
+	flag.BoolVar(&r.bare, "bare", false, "If set then the repo being opened will be expected to be bare")
+}
+
+func (r *repo) openRepo() error {
+	var err error
+	if r.Repo, err = dehub.OpenRepo(".", dehub.OpenBare(r.bare)); err != nil {
+		wd, _ := os.Getwd()
+		return fmt.Errorf("opening repo at %q: %w", wd, err)
+	}
+	return nil
+}

cmd/dehub/cmd_verify.go

@@ -15,8 +15,13 @@ func cmdVerify(ctx context.Context, cmd *dcmd.Cmd) {
 	rev := flag.String("rev", "HEAD", "Revision of commit to verify")
 	branch := flag.String("branch", "", "Branch that the revision is on. If not given then the currently checked out branch is assumed")
 
+	var repo repo
+	repo.initFlags(flag)
+
 	cmd.Run(func() (context.Context, error) {
-		repo := ctxRepo(ctx)
+		if err := repo.openRepo(); err != nil {
+			return nil, err
+		}
 
 		gitCommit, err := repo.GetGitRevision(plumbing.Revision(*rev))
 		if err != nil {

cmd/dehub/dcmd/dcmd.go

@@ -50,6 +50,14 @@ func (cmd *Cmd) getFlagSet() *flag.FlagSet {
 	return cmd.flagSet
 }
 
+func (cmd *Cmd) numFlags() int {
+	var n int
+	cmd.getFlagSet().VisitAll(func(*flag.Flag) {
+		n++
+	})
+	return n
+}
+
 // FlagSet returns a flag.Cmd instance on which parameter creation methods can
 // be called, e.g. String(...) or Int(...).
 func (cmd *Cmd) FlagSet() *flag.FlagSet {
@@ -77,11 +85,19 @@ func (cmd *Cmd) SubCmd(name, descr string, run func(context.Context, *Cmd)) {
 }
 
 func (cmd *Cmd) printUsageHead(subCmdTitle string) {
+	hasFlags := cmd.numFlags() > 0
+
 	var title string
 	if cmd.parent == nil {
-		title = fmt.Sprintf("USAGE: %s [flags]", cmd.binary)
+		title = fmt.Sprintf("USAGE: %s", cmd.binary)
+		if hasFlags {
+			title += " [flags]"
+		}
 	} else {
-		title = fmt.Sprintf("%s [%s flags]", cmd.name, cmd.name)
+		title = fmt.Sprintf("%s", cmd.name)
+		if hasFlags {
+			title += fmt.Sprintf(" [%s flags]", cmd.name)
+		}
 	}
 
 	if subCmdTitle != "" {
@@ -92,15 +108,20 @@ func (cmd *Cmd) printUsageHead(subCmdTitle string) {
 
 	if cmd.parent == nil {
 		fmt.Printf("\n%s\n\n", title)
-		fmt.Print("### FLAGS ###\n\n")
 	} else {
 		cmd.parent.printUsageHead(title)
-		fmt.Printf("### %s FLAGS ###\n\n", strings.ToUpper(cmd.name))
 	}
 
+	if hasFlags {
+		if cmd.parent == nil {
+			fmt.Print("### FLAGS ###\n\n")
+		} else {
+			fmt.Printf("### %s FLAGS ###\n\n", strings.ToUpper(cmd.name))
+		}
 		cmd.getFlagSet().PrintDefaults()
 		fmt.Print("\n")
 	}
+}
 
 // Run performs the comand. It starts by parsing all flags in the Cmd's FlagSet,
 // and possibly exiting with a usage message if appropriate. It will then

cmd/dehub/main.go

@@ -2,44 +2,18 @@ package main
 
 import (
 	"context"
-	"fmt"
-	"os"
 
-	"dehub.dev/src/dehub.git"
 	"dehub.dev/src/dehub.git/cmd/dehub/dcmd"
 )
 
-type cmdCtxKey int
-
-const (
-	cmdCtxKeyRepo cmdCtxKey = iota
-)
-
-func ctxRepo(ctx context.Context) *dehub.Repo {
-	repo, ok := ctx.Value(cmdCtxKeyRepo).(*dehub.Repo)
-	if !ok {
-		panic("repo not initialized on the command context")
-	}
-	return repo
-}
-
 func main() {
 	cmd := dcmd.New()
-	flag := cmd.FlagSet()
-	bare := flag.Bool("bare", false, "If set then dehub will expect to be working with a bare repo")
-
 	cmd.SubCmd("commit", "commits staged changes to the head of the current branch", cmdCommit)
 	cmd.SubCmd("verify", "verifies one or more commits as having the proper credentials", cmdVerify)
 	cmd.SubCmd("hook", "use dehub as a git hook", cmdHook)
 	cmd.SubCmd("combine", "Combine multiple change and credential commits into a single commit", cmdCombine)
 
 	cmd.Run(func() (context.Context, error) {
-		repo, err := dehub.OpenRepo(".", dehub.OpenBare(*bare))
-		if err != nil {
-			wd, _ := os.Getwd()
-			return nil, fmt.Errorf("failed to OpenRepo at %q: %w", wd, err)
-		}
-
-		return context.WithValue(context.Background(), cmdCtxKeyRepo, repo), nil
+		return context.Background(), nil
 	})
 }