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package color

Defined in github.com/fatih/color/.

Description

Package color is an ANSI color package to output colorized or SGR defined output to the standard output. The API can be used in several way, pick one that suits you.

Use simple and default helper functions with predefined foreground colors:

color.Cyan("Prints text in cyan.")

// a newline will be appended automatically
color.Blue("Prints %s in blue.", "text")

// More default foreground colors..
color.Red("We have red")
color.Yellow("Yellow color too!")
color.Magenta("And many others ..")

However there are times where custom color mixes are required. Below are some examples to create custom color objects and use the print functions of each separate color object.

// Create a new color object
c := color.New(color.FgCyan).Add(color.Underline)
c.Println("Prints cyan text with an underline.")

// Or just add them to New()
d := color.New(color.FgCyan, color.Bold)
d.Printf("This prints bold cyan %s\n", "too!.")

// Mix up foreground and background colors, create new mixes!
red := color.New(color.FgRed)

boldRed := red.Add(color.Bold)
boldRed.Println("This will print text in bold red.")

whiteBackground := red.Add(color.BgWhite)
whiteBackground.Println("Red text with White background.")

You can create PrintXxx functions to simplify even more:

// Create a custom print function for convenient
red := color.New(color.FgRed).PrintfFunc()
red("warning")
red("error: %s", err)

// Mix up multiple attributes
notice := color.New(color.Bold, color.FgGreen).PrintlnFunc()
notice("don't forget this...")

Or create SprintXxx functions to mix strings with other non-colorized strings:

yellow := New(FgYellow).SprintFunc()
red := New(FgRed).SprintFunc()

fmt.Printf("this is a %s and this is %s.\n", yellow("warning"), red("error"))

info := New(FgWhite, BgGreen).SprintFunc()
fmt.Printf("this %s rocks!\n", info("package"))

Windows support is enabled by default. All Print functions works as intended. However only for color.SprintXXX functions, user should use fmt.FprintXXX and set the output to color.Output:

fmt.Fprintf(color.Output, "Windows support: %s", color.GreenString("PASS"))

info := New(FgWhite, BgGreen).SprintFunc()
fmt.Fprintf(color.Output, "this %s rocks!\n", info("package"))

Using with existing code is possible. Just use the Set() method to set the standard output to the given parameters. That way a rewrite of an existing code is not required.

// Use handy standard colors.
color.Set(color.FgYellow)

fmt.Println("Existing text will be now in Yellow")
fmt.Printf("This one %s\n", "too")

color.Unset() // don't forget to unset

// You can mix up parameters
color.Set(color.FgMagenta, color.Bold)
defer color.Unset() // use it in your function

fmt.Println("All text will be now bold magenta.")

There might be a case where you want to disable color output (for example to pipe the standard output of your app to somewhere else). `Color` has support to disable colors both globally and for single color definition. For example suppose you have a CLI app and a `--no-color` bool flag. You can easily disable the color output with:

var flagNoColor = flag.Bool("no-color", false, "Disable color output")

if *flagNoColor {
	color.NoColor = true // disables colorized output
}

It also has support for single color definitions (local). You can disable/enable color output on the fly:

c := color.New(color.FgCyan)
c.Println("Prints cyan text")

c.DisableColor()
c.Println("This is printed without any color")

c.EnableColor()
c.Println("This prints again cyan...")

color is referenced in 296 repositories

github.com/fatih/color github.com/concourse/fly github.com/amyhaber/cnki-downloader

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