cli/command/completion: change FileNames to return a cobra.CompletionFunc

It's adding a slight indirection by constructing a function when called,
but makes the completion functions more consistent, the signature easier
to read, and making the return type a [cobra.CompletionFunc] makes it
more transparent what it's intended for, and helps discovery of functions
that provide completion.

[cobra.CompletionFunc]: https://pkg.go.dev/github.com/spf13/cobra#CompletionFunc

Signed-off-by: Sebastiaan van Stijn <[email protected]>

Author: thaJeztah

cli/command/completion/functions.go

@@ -136,8 +136,10 @@ func FromList(options ...string) cobra.CompletionFunc {
 // FileNames is a convenience function to use [cobra.ShellCompDirectiveDefault],
 // which indicates to let the shell perform its default behavior after
 // completions have been provided.
-func FileNames(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
-	return nil, cobra.ShellCompDirectiveDefault
+func FileNames() cobra.CompletionFunc {
+	return func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		return nil, cobra.ShellCompDirectiveDefault
+	}
 }
 
 var commonPlatforms = []string{

cli/command/completion/functions_test.go

@@ -185,7 +185,7 @@ func TestCompleteEnvVarNames(t *testing.T) {
 }
 
 func TestCompleteFileNames(t *testing.T) {
-	values, directives := FileNames(nil, nil, "")
+	values, directives := FileNames()(nil, nil, "")
 	assert.Check(t, is.Equal(directives, cobra.ShellCompDirectiveDefault))
 	assert.Check(t, is.Len(values, 0))
 }

cli/command/container/completion.go

@@ -123,7 +123,7 @@ func addCompletions(cmd *cobra.Command, dockerCLI completion.APIClientProvider)
 	_ = cmd.RegisterFlagCompletionFunc("cap-drop", completeLinuxCapabilityNames)
 	_ = cmd.RegisterFlagCompletionFunc("cgroupns", completeCgroupns())
 	_ = cmd.RegisterFlagCompletionFunc("env", completion.EnvVarNames())
-	_ = cmd.RegisterFlagCompletionFunc("env-file", completion.FileNames)
+	_ = cmd.RegisterFlagCompletionFunc("env-file", completion.FileNames())
 	_ = cmd.RegisterFlagCompletionFunc("ipc", completeIpc(dockerCLI))
 	_ = cmd.RegisterFlagCompletionFunc("link", completeLink(dockerCLI))
 	_ = cmd.RegisterFlagCompletionFunc("log-driver", completeLogDriver(dockerCLI))

cli/command/container/exec.go

@@ -79,7 +79,7 @@ func newExecCommand(dockerCLI command.Cli) *cobra.Command {
 	flags.SetAnnotation("workdir", "version", []string{"1.35"})
 
 	_ = cmd.RegisterFlagCompletionFunc("env", completion.EnvVarNames())
-	_ = cmd.RegisterFlagCompletionFunc("env-file", completion.FileNames)
+	_ = cmd.RegisterFlagCompletionFunc("env-file", completion.FileNames())
 
 	return cmd
 }

cli/command/context/import.go

@@ -21,7 +21,7 @@ func newImportCommand(dockerCLI command.Cli) *cobra.Command {
 			return runImport(dockerCLI, args[0], args[1])
 		},
 		// TODO(thaJeztah): this should also include "-"
-		ValidArgsFunction:     completion.FileNames,
+		ValidArgsFunction:     completion.FileNames(),
 		DisableFlagsInUseLine: true,
 	}
 	return cmd

cli/command/service/create.go

@@ -83,7 +83,7 @@ func newCreateCommand(dockerCLI command.Cli) *cobra.Command {
 
 	_ = cmd.RegisterFlagCompletionFunc(flagMode, completion.FromList("replicated", "global", "replicated-job", "global-job"))
 	_ = cmd.RegisterFlagCompletionFunc(flagEnv, completion.EnvVarNames()) // TODO(thaJeztah): flagEnvRemove (needs to read current env-vars on the service)
-	_ = cmd.RegisterFlagCompletionFunc(flagEnvFile, completion.FileNames)
+	_ = cmd.RegisterFlagCompletionFunc(flagEnvFile, completion.FileNames())
 	_ = cmd.RegisterFlagCompletionFunc(flagNetwork, completion.NetworkNames(dockerCLI))
 	_ = cmd.RegisterFlagCompletionFunc(flagRestartCondition, completion.FromList("none", "on-failure", "any"))
 	_ = cmd.RegisterFlagCompletionFunc(flagRollbackOrder, completion.FromList("start-first", "stop-first"))