Work in progress: experimentation with console output

Several open issues mention problems with interaction of the
global `--encoding=` flag and the Encoders and PostRun fields of
command structs. This branch contains experimental refactors that
explore approaches to consistent command execution patterns across
offline, online and http modes.

Specific tickets:

- ipfs/kubo#7050 json encoding for `ls`
- ipfs/kubo#1121 json encoding for `add`
- ipfs/kubo#5594 json encoding for `stats bw`
- ipfs#115 postrun design

Possibly related:

- ipfs/kubo#6640 global flags on subcommands

Incomplete PRs:

- ipfs/kubo#5620 json for 'stat'

cli/parse.go

@@ -45,16 +45,6 @@ func Parse(ctx context.Context, input []string, stdin *os.File, root *cmds.Comma
 		return req, err
 	}
 
-	// if no encoding was specified by user, default to plaintext encoding
-	// (if command doesn't support plaintext, use JSON instead)
-	if enc := req.Options[cmds.EncLong]; enc == "" {
-		if req.Command.Encoders != nil && req.Command.Encoders[cmds.Text] != nil {
-			req.SetOption(cmds.EncLong, cmds.Text)
-		} else {
-			req.SetOption(cmds.EncLong, cmds.JSON)
-		}
-	}
-
 	return req, nil
 }
 

cli/run.go

@@ -102,8 +102,6 @@ func Run(ctx context.Context, root *cmds.Command,
 		return nil
 	}
 
-	cmd := req.Command
-
 	env, err := buildEnv(req.Context, req)
 	if err != nil {
 		printErr(err)
@@ -119,14 +117,6 @@ func Run(ctx context.Context, root *cmds.Command,
 		return err
 	}
 
-	encTypeStr, _ := req.Options[cmds.EncLong].(string)
-	encType := cmds.EncodingType(encTypeStr)
-
-	// use JSON if text was requested but the command doesn't have a text-encoder
-	if _, ok := cmd.Encoders[encType]; encType == cmds.Text && !ok {
-		req.Options[cmds.EncLong] = cmds.JSON
-	}
-
 	re, err := NewResponseEmitter(stdout, stderr, req)
 	if err != nil {
 		printErr(err)

command.go

@@ -11,6 +11,7 @@ package cmds
 import (
 	"errors"
 	"fmt"
+	"io"
 	"strings"
 
 	files "github.com/ipfs/go-ipfs-files"
@@ -30,6 +31,10 @@ type Function func(*Request, ResponseEmitter, Environment) error
 // PostRunMap is the map used in Command.PostRun.
 type PostRunMap map[PostRunType]func(Response, ResponseEmitter) error
 
+// DisplayCLI supplies an function for console output in local
+// processes in combination with a text Encoder.
+type DisplayCLI func(res Response, stdout, stderr io.Writer) error
+
 // Command is a runnable command, with input arguments and options (flags).
 // It can also have Subcommands, to group units of work into sets.
 type Command struct {
@@ -62,6 +67,10 @@ type Command struct {
 	// the local process.
 	PostRun PostRunMap
 
+	// DisplayCLI is for text output in local process in
+	// combination with 'text' Encoder.
+	DisplayCLI DisplayCLI
+
 	// Encoders encode results from Run (and/or PostRun) in the desired
 	// encoding.
 	Encoders EncoderMap

executor.go

@@ -2,6 +2,7 @@ package cmds
 
 import (
 	"context"
+	"os"
 )
 
 type Executor interface {
@@ -51,9 +52,20 @@ func (x *executor) Execute(req *Request, re ResponseEmitter, env Environment) er
 		}
 	}
 
-	// contains the error returned by PostRun
+	// contains the error returned by DisplayCLI or PostRun
 	errCh := make(chan error, 1)
-	if cmd.PostRun != nil {
+	if cmd.DisplayCLI != nil && GetEncoding(req, "json") == "text" {
+		var (
+			res   Response
+		)
+
+		re, res = NewChanResponsePair(req)
+
+		go func() {
+			defer close(errCh)
+			errCh <- cmd.DisplayCLI(res, os.Stdout, os.Stderr)
+		}()
+	} else if cmd.PostRun != nil {
 		if typer, ok := re.(interface {
 			Type() PostRunType
 		}); ok && cmd.PostRun[typer.Type()] != nil {

http/client.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"strings"
 
 	"github.com/ipfs/go-ipfs-cmds"
@@ -132,6 +133,11 @@ func (c *client) Execute(req *cmds.Request, re cmds.ResponseEmitter, env cmds.En
 		}
 	}
 
+	if cmd.DisplayCLI != nil &&
+		cmds.GetEncoding(req, cmds.Undefined) == cmds.Text {
+		return cmd.DisplayCLI(res, os.Stdout, os.Stderr)
+	}
+
 	return cmds.Copy(re, res)
 }