add_argument should not overwrite properties defined in class member.

There is a very common practice in scripts, to allow both "long syntax" and shorter versions of some argument name. [The documentation] (https://github.com/swansonk14/typed-argument-parser?tab=readme-ov-file#adding-special-argument-behavior) suggests using add_argument to achieve this:

from tap import Tap

class MyTap(Tap):
    argument_with_really_long_name: int

    def configure(self):
        self.add_argument('-arg', '--argument_with_really_long_name')

However, In the case where I had defined properties on this argument, the operation will overwrite these

from tap import Tap

class MyTap(Tap):
    argument_with_really_long_name: int = 5  # A description for this long argument

    def configure(self):
        self.add_argument('-arg', '--argument_with_really_long_name')

In this case, the default value and the help description will be lost. In my project, we have many such arguments, sometimes defined with more complex properties such as list[Literal] types - it is a shame that the second we want to allow a shorter argument name, we lose all the powerful Tap features that allow defining argument properties. An example from our code:

from typing import Literal, get_args
from tap import Tap

DebugOptionsType = Literal["INFO", "DEBUG", "WARNING", "ERROR", "CRITICAL"]

class CloudDebuggerOptions(Tap):
    aws_profile: str = "default"  # The AWS profile to use
    debug_levels: list[DebugOptionsType] = []  # A list of debug messages to receive

I want to allow shorter names here - and so have to add all the following lines

    def configure(self) -> None:
        self.add_argument("-a", "--aws-profile", dest="aws_profile", default="default", help="The AWS profile to use")
        self.add_argument(
            "-d",
            "--debug-levels",
            dest="debug_levels",
            nargs="+",
            choices=get_args(DebugOptionsType),
            default=[],
            help="A list of debug messages to receive",
        )

by the way, the same problem is present if we want to allow the CLI options to be in kebab-case (the linux standard) as opposed to snake_case, as can be seen above (since you cannot define class member names using kebab-case in python).

PROPOSAL

Only overwrite the specific add_argument options being used, and take the rest from the class member. Or, possible, make some simpler syntax that allows assigning an alternative argument name

swansonk14 / typed-argument-parser

add_argument should not overwrite properties defined in class member. #131

PROPOSAL