readline: Terminal breaks with a newline `\n` prompt about readline HOT 4 CLOSED

Hi @str1ngs-bytes

Thank you for the bug report. Are you able to provide a little more detail please? A screenshot of how it breaks, what "breaks" looks like, and what platform you're running it from (terminal emulator, OS), etc.

I use \n a lot and haven't run into any breakages because of \n however the CLI landscape is a diverse one so without a little more detail it will be impossible for me to replicate your issue and fix the problem.

from readline.

I am extremely sorry for opening the issue here. The issue actually is in readline lib which I am using and when I set
SetPrompt ("User Jhon\n$ ") breaks the shell kind of it repeatedly prints the prompt on every key press. Is there a quick fix or a workaround that I can use the '\n' is important in my case.

Terminal Output :
User Jhon
User Jhon
User Jhon
User Jhon
$ abcd

from readline.

Ahh ok, that makes sense. :)

The prompt it intended to be only a single line by design however the effect you're seeing is definitely readline not handling the new line correctly (it should either strip it or be rewritten to support multi-line prompts).

The reason I say it's not intended to be multi-line "by design" is because the additional helper detail is intended to be supplied via the "hint" text: https://github.com/lmorg/readline/blob/master/instance.go#L59

So you'd have code that might look a little like:

// WARNING: this code has been directly typed into Github and thus untested. So it might not compile verbatim.

rl.SetPrompt("$ ")
rl.HintText = func([]rune, int) []rune {
    return []rune("User Jhon")
}()

The idea behind this design is so that the additional line in most people's multi-line prompts can be context aware. Each time you press a key the HintText function (which is the func you've assigned to the HintText variable above) gets called with []rune being the entire text that the user has inputted thus far, and the int being the cursor position.

This is means you can do some cool stuff like:

// WARNING: this code has been directly typed into Github and thus untested. So it might not compile verbatim.

rl.SetPrompt("$ ")
rl.HintText = func(text []rune, pos int) []rune {
    hint := fmt.Sprintf("You have typed: %s\nYour cursor position is %d", string(text), pos)

    return []rune(hint)
}()

That all said, I'm not totally against adding multi-line prompt support to readline. It just wasn't part of the original intended design.

As an aside, you can also change the formatting of the hint text via HintFormatting (https://github.com/lmorg/readline/blob/master/instance.go#L64):

// WARNING: this code has been directly typed into Github and thus untested. So it might not compile verbatim.

rl.SetPrompt("$ ")
rl.HintText = func([]rune, int) []rune {
    return []rune("User Jhon")
}()

rl.HintFormatting = ""         // no formatting
rl.HintFormatting = "\x1b[41m" // red background
// etc

from readline.

I'm going to close this ticket. If you feel I haven't solved your problem then I'm happy to re-open.

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