argparse custom action OOP

Question

i'm new to argparse and oop in python, i want to use a custom action in argparse, i have read the docs . basically i just want to run a function if an argument is used, i don't know what the hell i'm supposed to do, create another class and do a __call__ and put my function code in there? cause that doesn't work either.

class UserSearch:
    def __init__(self) -> None:
        self.args = self.get_args()
        self.data = ItemData(domains[self.args.type], self.args.name).output()

    def get_args(self):
        parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter)   
        parser.add_argument(
            "-c",
            "--color",
            help="Color of the item you want to search for.",
            default="",
            nargs="*",
            action=self.getcolors(),
        )

        return parser.parse_args()

    def getcolors(self):
        args = self.args
        data = self.data
        user_selection = []
        for k in args.color:
            sregex = re.compile(fr".*{k}.*", re.I | re.U)
            for i in range(len(data)):
                for j in list(data[i]["color"].keys()):
                    # print(data[i])
                    try:
                        if sregex.match(j).group(0):
                            user_selection.append(data[i])
                    except AttributeError:
                        continue
        return user_selection

now as u can see what i want to do is pretty simple, i've tried for 2 days to find solution and i just can't.

Answer 1

Parsing is best done by a separate function, that can be called when used as a script. It should not be performed by an import . Getting user input, from command line or other source should be separate from the action (class definition and use).

def get_args(argv=None):
        parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter)   
        parser.add_argument(
            "-c",
            "--color",
            help="Color of the item you want to search for.",
            default="",
            nargs="*",
            action=self.getcolors(argv),
        )

        return parser.parse_args()

class UserSearch:
    def __init__(self, args) -> None:
        self.args = args
        self.data = ItemData(domains[self.args.type], self.args.name).output()
    # your parser doesn't specify a 'type`' argument
    # not 'name' either


    def getcolors(self):
        args = self.args
        data = self.data
        user_selection = []
        for k in args.color:
            sregex = re.compile(fr".*{k}.*", re.I | re.U)
            for i in range(len(data)):
                for j in list(data[i]["color"].keys()):
                    # print(data[i])
                    try:
                        if sregex.match(j).group(0):
                            user_selection.append(data[i])
                    except AttributeError:
                        continue
        return user_selection

if __name__ == '__main__':
    args = get_args()
    user = UserSearch(args)
    # use user

If ItemData is some sort of database fetcher or opener, you might want to separate that from the search .

While Python uses objects throughout (and argparse is a good example of module that defines classes), you, as the user, don't have to create a class to do your job. It may be a convenient way of organizing the task, but Python does not formally require it (in contrast to something like Java ).