Provide Write(), Stderr(), Printf() methods on App (desertbit#14)

* Provide Write() and Stderr() methods on App.

This allows consumers of the library to write in a manner that refreshes
the prompt because it goes through the Readline library.  This is useful
for background tasks or notifications to correctly redraw your screen.

This uses the readline terminal when available, otherwise it uses
os.Stdout.

README.md

@@ -43,13 +43,13 @@ app.AddCommand(&grumble.Command{
     },
 
     Run: func(c *grumble.Context) error {
-        fmt.Println("timeout:", c.Flags.Duration("timeout"))
-        fmt.Println("directory:", c.Flags.String("directory"))
-        fmt.Println("verbose:", c.Flags.Bool("verbose"))
+        c.App.Println("timeout:", c.Flags.Duration("timeout"))
+        c.App.Println("directory:", c.Flags.String("directory"))
+        c.App.Println("verbose:", c.Flags.Bool("verbose"))
 
         // Handle args.
-        fmt.Println("args:")
-        fmt.Println(strings.Join(c.Args, "\n"))
+        c.App.Println("args:")
+        c.App.Println(strings.Join(c.Args, "\n"))
 
         return nil
     },

app.go

@@ -123,13 +123,25 @@ func (a *App) Commands() *Commands {
 // PrintError prints the given error.
 func (a *App) PrintError(err error) {
 	if a.config.NoColor {
-		fmt.Printf("error: %v\n", err)
+		a.Printf("error: %v\n", err)
 	} else {
-		a.config.ErrorColor.Print("error: ")
-		fmt.Printf("%v\n", err)
+		a.config.ErrorColor.Fprint(a, "error: ")
+		a.Printf("%v\n", err)
 	}
 }
 
+// Printf formats according to a format specifier and writes to terminal output.
+// Printf writes to standard output if terminal output is not yet active.
+func (a *App) Printf(format string, args ...interface{}) (int, error) {
+	return fmt.Fprintf(a, format, args...)
+}
+
+// Println writes to terminal output followed by a newline.
+// Println writes to standard output if terminal output is not yet active.
+func (a *App) Println(args ...interface{}) (int, error) {
+	return fmt.Fprintln(a, args...)
+}
+
 // OnInit sets the function which will be executed before the first command
 // is executed. App flags can be handled here.
 func (a *App) OnInit(f func(a *App, flags FlagMap) error) {
@@ -167,6 +179,29 @@ func (a *App) SetPrintASCIILogo(f func(a *App)) {
 	}
 }
 
+// Write to the underlying output, using readline if available.
+func (a *App) Write(p []byte) (int, error) {
+	return a.Stdout().Write(p)
+}
+
+// Stdout returns a writer to Stdout, using readline if available.
+// Note that calling before Run() will return a different instance.
+func (a *App) Stdout() io.Writer {
+	if a.rl != nil {
+		return a.rl.Stdout()
+	}
+	return os.Stdout
+}
+
+// Stderr returns a writer to Stderr, using readline if available.
+// Note that calling before Run() will return a different instance.
+func (a *App) Stderr() io.Writer {
+	if a.rl != nil {
+		return a.rl.Stderr()
+	}
+	return os.Stderr
+}
+
 // AddCommand adds a new command.
 // Panics on error.
 func (a *App) AddCommand(cmd *Command) {

functions.go

@@ -34,10 +34,10 @@ import (
 
 func defaultInterruptHandler(a *App, count int) {
 	if count >= 2 {
-		fmt.Println("interrupted")
+		a.Println("interrupted")
 		os.Exit(1)
 	}
-	fmt.Println("input Ctrl-c once more to exit")
+	a.Println("input Ctrl-c once more to exit")
 }
 
 func defaultPrintHelp(a *App, shell bool) {
@@ -54,14 +54,14 @@ func defaultPrintHelp(a *App, shell bool) {
 
 	// Description.
 	if (len(a.config.Description)) > 0 {
-		fmt.Printf("\n%s\n", a.config.Description)
+		a.Printf("\n%s\n", a.config.Description)
 	}
 
 	// Usage.
 	if !shell {
-		fmt.Println()
-		printHeadline(a.config, "Usage:")
-		fmt.Printf("  %s [command]\n", a.config.Name)
+		a.Println()
+		printHeadline(a, "Usage:")
+		a.Printf("  %s [command]\n", a.config.Name)
 	}
 
 	// Group the commands by their help group if present.
@@ -101,9 +101,9 @@ func defaultPrintHelp(a *App, shell bool) {
 		}
 
 		if len(output) > 0 {
-			fmt.Println()
-			printHeadline(a.config, headline)
-			fmt.Printf("%s\n", columnize.Format(output, config))
+			a.Println()
+			printHeadline(a, headline)
+			a.Printf("%s\n", columnize.Format(output, config))
 		}
 	}
 
@@ -119,9 +119,9 @@ func defaultPrintHelp(a *App, shell bool) {
 		}
 		if hasSubCmds {
 			// Headline.
-			fmt.Println()
-			printHeadline(a.config, "Sub Commands:")
-			hp := headlinePrinter(a.config)
+			a.Println()
+			printHeadline(a, "Sub Commands:")
+			hp := headlinePrinter(a)
 
 			// Only print the first level of sub commands.
 			for _, c := range a.commands.list {
@@ -138,9 +138,9 @@ func defaultPrintHelp(a *App, shell bool) {
 					output = append(output, fmt.Sprintf("%s | %v", name, c.Help))
 				}
 
-				fmt.Println()
+				a.Println()
 				_, _ = hp(c.Name + ":")
-				fmt.Printf("%s\n", columnize.Format(output, config))
+				a.Printf("%s\n", columnize.Format(output, config))
 			}
 		}
 	}
@@ -150,7 +150,7 @@ func defaultPrintHelp(a *App, shell bool) {
 		printFlags(a, &a.flags)
 	}
 
-	fmt.Println()
+	a.Println()
 }
 
 func defaultPrintCommandHelp(a *App, cmd *Command, shell bool) {
@@ -162,16 +162,16 @@ func defaultPrintCommandHelp(a *App, cmd *Command, shell bool) {
 
 	// Help description.
 	if (len(cmd.LongHelp)) > 0 {
-		fmt.Printf("\n%s\n", cmd.LongHelp)
+		a.Printf("\n%s\n", cmd.LongHelp)
 	} else {
-		fmt.Printf("\n%s\n", cmd.Help)
+		a.Printf("\n%s\n", cmd.Help)
 	}
 
 	// Usage
 	if len(cmd.Usage) > 0 {
-		fmt.Println()
-		printHeadline(a.config, "Usage:")
-		fmt.Printf("  %s\n", cmd.Usage)
+		a.Println()
+		printHeadline(a, "Usage:")
+		a.Printf("  %s\n", cmd.Usage)
 	}
 
 	// Flags.
@@ -189,24 +189,26 @@ func defaultPrintCommandHelp(a *App, cmd *Command, shell bool) {
 			output = append(output, fmt.Sprintf("%s | %v", name, c.Help))
 		}
 
-		fmt.Println()
-		printHeadline(a.config, "Sub Commands:")
-		fmt.Printf("%s\n", columnize.Format(output, config))
+		a.Println()
+		printHeadline(a, "Sub Commands:")
+		a.Printf("%s\n", columnize.Format(output, config))
 	}
 
-	fmt.Println()
+	a.Println()
 }
 
-func headlinePrinter(c *Config) func(v ...interface{}) (int, error) {
-	if c.NoColor || c.HelpHeadlineColor == nil {
-		return fmt.Println
+func headlinePrinter(a *App) func(v ...interface{}) (int, error) {
+	if a.config.NoColor || a.config.HelpHeadlineColor == nil {
+		return a.Println
+	}
+	return func(v ...interface{}) (int, error) {
+		return a.config.HelpHeadlineColor.Fprintln(a, v...)
 	}
-	return c.HelpHeadlineColor.Println
 }
 
-func printHeadline(c *Config, s string) {
-	hp := headlinePrinter(c)
-	if c.HelpHeadlineUnderline {
+func printHeadline(a *App, s string) {
+	hp := headlinePrinter(a)
+	if a.config.HelpHeadlineUnderline {
 		_, _ = hp(s)
 		u := ""
 		for i := 0; i < len(s); i++ {
@@ -244,8 +246,8 @@ func printFlags(a *App, flags *Flags) {
 	}
 
 	if len(output) > 0 {
-		fmt.Println()
-		printHeadline(a.config, "Flags:")
-		fmt.Printf("%s\n", columnize.Format(output, config))
+		a.Println()
+		printHeadline(a, "Flags:")
+		a.Printf("%s\n", columnize.Format(output, config))
 	}
 }

sample/full/cmd/app.go

@@ -25,8 +25,6 @@
 package cmd
 
 import (
-	"fmt"
-
 	"github.com/desertbit/grumble"
 	"github.com/fatih/color"
 )
@@ -49,11 +47,11 @@ var App = grumble.New(&grumble.Config{
 
 func init() {
 	App.SetPrintASCIILogo(func(a *grumble.App) {
-		fmt.Println("                   _   _     ")
-		fmt.Println(" ___ ___ _ _ _____| |_| |___ ")
-		fmt.Println("| . |  _| | |     | . | | -_|")
-		fmt.Println("|_  |_| |___|_|_|_|___|_|___|")
-		fmt.Println("|___|                        ")
-		fmt.Println()
+		a.Println("                   _   _     ")
+		a.Println(" ___ ___ _ _ _____| |_| |___ ")
+		a.Println("| . |  _| | |     | . | | -_|")
+		a.Println("|_  |_| |___|_|_|_|___|_|___|")
+		a.Println("|___|                        ")
+		a.Println()
 	})
 }

sample/simple/cmd/app.go

@@ -52,13 +52,13 @@ func init() {
 			f.Duration("t", "timeout", time.Second, "timeout duration")
 		},
 		Run: func(c *grumble.Context) error {
-			fmt.Println("timeout:", c.Flags.Duration("timeout"))
-			fmt.Println("directory:", c.Flags.String("directory"))
-			fmt.Println("verbose:", c.Flags.Bool("verbose"))
+			c.App.Println("timeout:", c.Flags.Duration("timeout"))
+			c.App.Println("directory:", c.Flags.String("directory"))
+			c.App.Println("verbose:", c.Flags.Bool("verbose"))
 
 			// Handle args.
-			fmt.Println("args:")
-			fmt.Println(strings.Join(c.Args, "\n"))
+			c.App.Println("args:")
+			c.App.Println(strings.Join(c.Args, "\n"))
 
 			return nil
 		},
@@ -75,7 +75,7 @@ func init() {
 		Name: "root",
 		Help: "root the machine",
 		Run: func(c *grumble.Context) error {
-			fmt.Println(c.Flags.String("directory"))
+			c.App.Println(c.Flags.String("directory"))
 			return fmt.Errorf("failed!")
 		},
 	})