Incredibly simple way to cache the output of a function - useful with unreliable LLM APIs

cached_fn.py

import os

def cached_fn(dir_name: str, file_name: str, fn, verbose=True):
    """
    Base the output of a function on a file.

    If the file already exists, use it instead of running the function.

    If the function was executed, write its output to the provided `dir_name` and `file_name`.

    Example:

    >>> script = cached_fn(
    >>>    dir_name,
    >>>    "script",
    >>>    lambda: chat_with_ai(
    >>>        generate_script_prompt_system,
    >>>        generate_script_prompt.format(title=topic, content=content_to_answer),
    >>>        model="gpt-4"
    >>>    )
    >>> )

    Another Example:

    >>> one_and_one = cached_fn(
    >>>    dir_name,
    >>>    "add_one_and_one",
    >>>    lambda: 1 + 1
    >>> )
    """
    output_filename = f"{dir_name}/{file_name}.txt"
    if os.path.isfile(output_filename):
        with open(output_filename) as f:
            output = f.read()
    else:
        output = fn()
        with open(output_filename, 'w') as f:
            f.write(output)

    if verbose:
        print("================================================================")
        print(output)

    return output