Make your Python user scripts delightful with `prompt_toolkit`

README.md

Make your Python user scripts delightful with prompt_toolkit

When writing Python scripts, I ask for user input all the time. This input often has a fixed set of options, those options are usually not fully listed out to the user, the user has to type them out while making no typos, and then we have to do validation afterwards to make sure they picked something valid.

Recently I discovered the prompt_toolkit Python library, which fixes all this.

The library actually has lots of features, but the one that is relevant is this nice dropdown that lets you pick an item from pre-defined options. It saves time for the end-user and the script writer, and it'll delight anyone seeing it for the first time.

Code example below!

demo.gif

prompt_example.py

# pip install prompt_toolkit
from prompt_toolkit.validation import Validator
from prompt_toolkit import PromptSession
from prompt_toolkit.completion import FuzzyWordCompleter


def prompt_options(options: list, prompt_text: str) -> str:
    option_set = set(options)
    validator = Validator.from_callable(
        lambda x: x in option_set,
        error_message="Invalid option!",
        move_cursor_to_end=True
    )
    completer = FuzzyWordCompleter(options)
    session = PromptSession(prompt_text, validator=validator, completer=completer)
    return session.prompt(pre_run=session.default_buffer.start_completion)


opts = sorted(["Trombone", "Trumpet", "Mayonnaise", "Saxophone", "Violin", "Piano", "Guitar"])

instrument = prompt_options(opts, "Choose an instrument: ")

print(f"You chose: {instrument}")