# `readline` — GNU readline interface

`readline` 모듈은 파이썬 인터프리터에서 완성(completion)과 히스토리 파일의 읽기/쓰기를 용이하게 하는 여러 함수를 정의합니다. 이 모듈은 직접 사용하거나, 대화식 프롬프트에서 파이썬 식별자 완성을 지원하는 `rlcompleter` 모듈을 통해 사용할 수 있습니다. 이 모듈을 사용하여 설정한 내용은 인터프리터의 대화식 프롬프트와 내장 `input()` 함수가 제공하는 프롬프트의 동작에 영향을 줍니다.

Readline keybindings may be configured via an initialization file, typically `.inputrc` in your home directory. See Readline Init File in the GNU Readline manual for information about the format and allowable constructs of that file, and the capabilities of the Readline library in general.

참고

The underlying Readline library API may be implemented by the `libedit` library instead of GNU readline. On macOS the `readline` module detects which library is being used at run time.

The configuration file for `libedit` is different from that of GNU readline. If you programmatically load configuration strings you can check for the text “libedit” in `readline.__doc__` to differentiate between GNU readline and libedit.

If you use editline/`libedit` readline emulation on macOS, the initialization file located in your home directory is named `.editrc`. For example, the following content in `~/.editrc` will turn ON vi keybindings and TAB completion:

    python:bind -v
    python:bind ^I rl_complete

## 초기화 파일

다음 함수는 초기화 파일 및 사용자 구성과 관련이 있습니다:

`readline.``parse_and_bind`(string)

  Execute the init line provided in the string argument. This calls `rl_parse_and_bind()` in the underlying library.

`readline.``read_init_file`([filename])

  Execute a readline initialization file. The default filename is the last filename used. This calls `rl_read_init_file()` in the underlying library.

## 줄 버퍼

다음 함수는 라인 버퍼에 대해 작용합니다:

`readline.``get_line_buffer`()

  Return the current contents of the line buffer (`rl_line_buffer` in the underlying library).

`readline.``insert_text`(string)

  Insert text into the line buffer at the cursor position. This calls `rl_insert_text()` in the underlying library, but ignores the return value.

`readline.``redisplay`()

  Change what’s displayed on the screen to reflect the current contents of the line buffer. This calls `rl_redisplay()` in the underlying library.

## 히스토리 파일

다음 함수는 히스토리 파일에 대해 작용합니다:

`readline.``read_history_file`([filename])

  Load a readline history file, and append it to the history list. The default filename is `~/.history`. This calls `read_history()` in the underlying library.

`readline.``write_history_file`([filename])

  Save the history list to a readline history file, overwriting any existing file. The default filename is `~/.history`. This calls `write_history()` in the underlying library.

`readline.``append_history_file`(nelements[, filename])

  Append the last nelements items of history to a file. The default filename is `~/.history`. The file must already exist. This calls `append_history()` in the underlying library. This function only exists if Python was compiled for a version of the library that supports it.

  버전 3.5에 추가.

`readline.``get_history_length`()
`readline.``set_history_length`(length)

  Set or return the desired number of lines to save in the history file. The `write_history_file()` function uses this value to truncate the history file, by calling `history_truncate_file()` in the underlying library. Negative values imply unlimited history file size.

## 히스토리 목록

다음 함수는 전역 히스토리 목록에 대해 작용합니다:

`readline.``clear_history`()

  Clear the current history. This calls `clear_history()` in the underlying library. The Python function only exists if Python was compiled for a version of the library that supports it.

`readline.``get_current_history_length`()

  현재 히스토리에 있는 항목 수를 반환합니다. (이것은 히스토리 파일에 기록될 최대 줄 수를 반환하는 `get_history_length()`와 다릅니다.)

`readline.``get_history_item`(index)

  Return the current contents of history item at index. The item index is one-based. This calls `history_get()` in the underlying library.

`readline.``remove_history_item`(pos)

  Remove history item specified by its position from the history. The position is zero-based. This calls `remove_history()` in the underlying library.

`readline.``replace_history_item`(pos, line)

  Replace history item specified by its position with line. The position is zero-based. This calls `replace_history_entry()` in the underlying library.

`readline.``add_history`(line)

  Append line to the history buffer, as if it was the last line typed. This calls `add_history()` in the underlying library.

`readline.``set_auto_history`(enabled)

  Enable or disable automatic calls to `add_history()` when reading input via readline. The enabled argument should be a Boolean value that when true, enables auto history, and that when false, disables auto history.

  버전 3.6에 추가.

  CPython 구현 상세: Auto history is enabled by default, and changes to this do not persist across multiple sessions.

## 시동 훅

`readline.``set_startup_hook`([function])

  Set or remove the function invoked by the `rl_startup_hook` callback of the underlying library. If function is specified, it will be used as the new hook function; if omitted or `None`, any function already installed is removed. The hook is called with no arguments just before readline prints the first prompt.

`readline.``set_pre_input_hook`([function])

  Set or remove the function invoked by the `rl_pre_input_hook` callback of the underlying library. If function is specified, it will be used as the new hook function; if omitted or `None`, any function already installed is removed. The hook is called with no arguments after the first prompt has been printed and just before readline starts reading input characters. This function only exists if Python was compiled for a version of the library that supports it.

## 완성

다음 함수는 사용자 정의 단어 완성 기능 구현과 관련이 있습니다. 이것은 일반적으로 Tab 키로 작동하며, 입력되는 단어를 제안하고 자동으로 완성할 수 있습니다. 기본적으로, Readline은 대화식 인터프리터를 위해 파이썬 식별자를 완성하는 `rlcompleter`에서 사용하도록 설정되어 있습니다. `readline` 모듈을 사용자 정의 완성기와 함께 사용하려면, 다른 단어 구분자 집합을 설정해야 합니다.

`readline.``set_completer`([function])

  완성 함수를 설정하거나 제거합니다. function이 지정되면 새 완성 함수로 사용됩니다; 생략하거나 `None`이면, 이미 설치된 완성 함수가 제거됩니다. 완성 함수는 문자열이 아닌 값을 반환할 때까지 `0`, `1`, `2` 등의 state에 대해 `function(text, state)`로 호출됩니다. text로 시작하는 다음으로 가능한 완성을 반환해야 합니다.

  The installed completer function is invoked by the entry_func callback passed to `rl_completion_matches()` in the underlying library. The text string comes from the first parameter to the `rl_attempted_completion_function` callback of the underlying library.

`readline.``get_completer`()

  완성 함수나, 완성 함수가 설정되지 않았으면 `None`을 얻습니다.

`readline.``get_completion_type`()

  Get the type of completion being attempted. This returns the `rl_completion_type` variable in the underlying library as an integer.

`readline.``get_begidx`()
`readline.``get_endidx`()

  Get the beginning or ending index of the completion scope. These indexes are the start and end arguments passed to the `rl_attempted_completion_function` callback of the underlying library. The values may be different in the same input editing scenario based on the underlying C readline implementation. Ex: libedit is known to behave differently than libreadline.

`readline.``set_completer_delims`(string)
`readline.``get_completer_delims`()

  Set or get the word delimiters for completion. These determine the start of the word to be considered for completion (the completion scope). These functions access the `rl_completer_word_break_characters` variable in the underlying library.

`readline.``set_completion_display_matches_hook`([function])

  Set or remove the completion display function. If function is specified, it will be used as the new completion display function; if omitted or `None`, any completion display function already installed is removed. This sets or clears the `rl_completion_display_matches_hook` callback in the underlying library. The completion display function is called as `function(substitution, [matches], longest_match_length)` once each time matches need to be displayed.

## 예제

다음 예는 `readline` 모듈의 히스토리 읽기와 쓰기 함수를 사용하여 사용자의 홈 디렉터리에서 `.python_history`라는 이름의 히스토리 파일을 자동으로 로드하고 저장하는 방법을 보여줍니다. 아래 코드는 일반적으로 사용자의 `PYTHONSTARTUP` 파일에서 대화식 세션 중에 자동으로 실행됩니다.

    import atexit
    import os
    import readline

    histfile = os.path.join(os.path.expanduser("~"), ".python_history")
    try:
        readline.read_history_file(histfile)
        # default history len is -1 (infinite), which may grow unruly
        readline.set_history_length(1000)
    except FileNotFoundError:
        pass

    atexit.register(readline.write_history_file, histfile)

이 코드는 실제로 파이썬이 대화형 모드로 실행될 때 자동으로 실행됩니다 (Readline 구성을 참조하십시오).

다음 예는 같은 목표를 달성하지만 새 히스토리를 덧붙이기만 해서 동시적인(concurrent) 대화형 세션을 지원합니다.

    import atexit
    import os
    import readline
    histfile = os.path.join(os.path.expanduser("~"), ".python_history")

    try:
        readline.read_history_file(histfile)
        h_len = readline.get_current_history_length()
    except FileNotFoundError:
        open(histfile, 'wb').close()
        h_len = 0

    def save(prev_h_len, histfile):
        new_h_len = readline.get_current_history_length()
        readline.set_history_length(1000)
        readline.append_history_file(new_h_len - prev_h_len, histfile)
    atexit.register(save, h_len, histfile)

다음 예는 히스토리 저장/복원을 지원하도록 `code.InteractiveConsole` 클래스를 확장합니다.

    import atexit
    import code
    import os
    import readline

    class HistoryConsole(code.InteractiveConsole):
        def __init__(self, locals=None, filename="<console>",
                     histfile=os.path.expanduser("~/.console-history")):
            code.InteractiveConsole.__init__(self, locals, filename)
            self.init_history(histfile)

        def init_history(self, histfile):
            readline.parse_and_bind("tab: complete")
            if hasattr(readline, "read_history_file"):
                try:
                    readline.read_history_file(histfile)
                except FileNotFoundError:
                    pass
                atexit.register(self.save_history, histfile)

        def save_history(self, histfile):
            readline.set_history_length(1000)
            readline.write_history_file(histfile)