[Feature Request] Support for absl/ml_collections like syntax in Typer: --user-config cfg --user-config.data.value=X

[jeandut]

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Example Code

from __future__ import annotations
import re
import yaml

from typing import Annotated, Any

from ml_collections.config_dict import ConfigDict


app = typer.Typer(name="myapp")

def get_config(raw: str):
    with open(raw, 'r') as file
        cfg = yaml.unsafe_load(file.to_yaml()) 
    return cfg
    
def set_key_in_config(raw: str):
    if raw is None:
        return
    # Some regexp based logic navigating the configdict given by the user
    # such as this one, note that this is pseudocode
    assert len(re.findall(raw, "=")) == 1
    keys_value = raw.split("=")
    value = keys_value[-1]
    keys = keys_value[0]
    keys_accessed = keys.split(".")
    count_inner_access = len(keys_accessed)
    for key_accessed in keys_accessed:
       if pointer is None:
           pointer = cfg.key_accessed # Note that cfg should be accessible
       else:
           pointer = pointer.key_accessed
    pointer = value

@app.command()
def run(
    cfg: str = typer.Option(
        ...,
        "--user-config",
        "-UC",
        help="The config given by the user.",
        parser=get_config,
    ),
    cfg_kwargs: str = typer.Option(
         None,
         "--user-config.*", # Note the regexp syntax
         help="Set specific key of cfg",
         parse=set_key_in_config,
    ),

Description

Firstable thanks for the wonderful package !
ml_collections, a widely used package by Google, provides easydicts (nested dicts with key access using dot syntax) (ConfigDict) with lots and lots of added functionalities such as a nice CLI syntax when used in conjunction with absl (one of Typer's" competitor" by Google).
It allows the user to provide a config (say a dict) and to overwrite some of its values dynamically using CLI aka being able to write something like:

myapp run --user-config path/towards/dict/in/yaml --user-config.data.value=3 --user-config.key2=foo --user-config.key2=23.

Where path/towards/dict/in/yaml is loaded first then --user-config.* arguments are used to modify its values inplace.
In Typer with the introduction of the parser argument this would facilitate emulating this behavior using the code above. However two (maybe three) features are missing:

• being able to first evaluate --user-config before any other --user-config.* arguments aka having the notion of dependent options
• being able to pass a regexp instead of a string to typer.Option
• the = plays the role of the space aka there is no space between the arg and its value (note that this is not a key feature and one could allow the syntax --user-config.data.value 3 for instance).

What do you think ? Does it make sense ? Would there be a simpler way to emulate this behavior using Typer existing functionalities ?

Operating System

macOS

Operating System Details

No response

Typer Version

0.8.0

Python Version

3.9.18

Additional Context

No response