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Q&A

Vim key bindings not working in terminal python interpreter

+1
−0

MWE

To reproduce:

  1. Add bindkey -v to your ~/.zshrc.
  2. Invoke python interpreter: python.
  3. Type something into the prompt without hitting ENTER: this = "this" + "that".
  4. Press ESC and try any vim bindings successively: bb.

Problem

The behavior is not consistent. Sometimes the cursor highlighting does not match the mode (see Notes for code used), sometimes I have to press ESC before each vim key entry.

Notes

Using Arch Linux, st terminal, zsh, and python 3.10.9.

I am using the following code in my ~/.zshrc to change the cursor to indicate mode:

# change cursor shape for different vi modes
cursor_mode() {
    # See https://ttssh2.osdn.jp/manual/4/en/usage/tips/vim.html for cursor shapes
    cursor_block='\e[2 q'
    cursor_beam='\e[6 q'
    function zle-keymap-select {
        if [[ ${KEYMAP} == vicmd ]] ||
               [[ $1 = 'block' ]]; then
            echo -ne $cursor_block
        elif [[ ${KEYMAP} == main ]] ||
                 [[ ${KEYMAP} == viins ]] ||
                 [[ ${KEYMAP} = '' ]] ||
                 [[ $1 = 'beam' ]]; then
            echo -ne $cursor_beam
        fi
    }
    zle-line-init() {
        echo -ne $cursor_beam
    }
    zle -N zle-keymap-select
    zle -N zle-line-init
}
cursor_mode
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1 answer

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Python's interactive interpreter uses GNU Readline, so Bash's line interpreter, not Zle, which is Zsh's.

Therefore, when you enter python, the cursor either won't change or will change accordingly to what you have in .inputrc, which is GNU Readline's initialization file. Likewise for the Vi or Emacs input mode.

For a visual proof that zle-line-init and zle-keymap-select don't get to run while you are in Python, just modify the cursor variables to

#Warning: This will be annoying
cursor_block=a
cursor_beam=b

Restart Zsh and you will see that, while those characters are inserted as expected in the Zsh prompt, they are never inserted in the Python prompt.

Luckily, you can (at least according to my quick inspection) clone that Zle's behavior for GNU Readline:

# This goes in $HOME/.inputrc
set editing-mode vi
set show-mode-in-prompt on
set vi-cmd-mode-string "\1\e[2 q\2"
set vi-ins-mode-string "\1\e[6 q\2"
# Previous three lines are from https://stackoverflow.com/a/48449104

and then Python will behave consistently.

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1 comment thread

Works for me (1 comment)

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