Use `prompt_toolkit.prompt` if available

[sedrubal]

When prompt-toolkit is installed, you could use prompt_toolkit.prompt as drop-in-replacement of input or raw_input. This would make it possible to navigate with arrow keys and Ctrl+A and Ctrl+E and more.

Example code:

Instead of:

click/click/termui.py

Line 17 in da4a182

visible_prompt_func = raw_input

you could use this:

try:
    from prompt_toolkit import prompt as visible_prompt_func
except ImportError:
    visible_prompt_func = raw_input

Related: #181 and #173

If you want, I can make a pull request.

---

Click: 6.7
Python 3.7

[davidism]

I'm open to reviewing something that allows customizing the prompt, if it's not possible already, but I do not want to add these sorts of optional imports that change behavior.

[sedrubal]

Ok. So do you think it is ok to add prompt_toolkit as dependency and always use prompt_toolkit.prompt as visible_prompt_func?

[davidism]

No, that's what I don't want.

[sedrubal]

Alright. So I close this issue, as there are other issues about enhancing the prompt.

[kdeldycke]

For context, a reference to prompt_toolkit has been proposed to Click documentation at #3826.