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