Python structural patterns - MVC

mvc.py

"""
The Separation of Concerns (SoC) is a design principle for separating a computer program into distinct sections.
With the Model View Controller (MVC) pattern we separate the out the data model, our visual representation or view, 
and the controller that decides what model data to show on the view.
"""


class PriceModel:
    stocks = {
        "FB": "Facebook",
        "AMZN": "Amazon",
        "AAPL": "Apple",
        "NFLX": "Netflix",
        "GOOG": "Google",
    }

    def get_stock_name(self, stock_code):
        return self.stocks[stock_code]

    def get_stock_code(self, stock_name):
        reverse_dict = {v: k for k, v in self.stocks.items()}
        return reverse_dict[stock_name]


class PriceView:
    def __init__(self):
        print("***** MVC Example *****")
        details = [
            "Here we can do lookups for FAANG stocks! Options are:",
            "- 's' to lookup by stock name.",
            "- 't' to lookup by stock ticker.",
            "- 'e' to exit.",
        ]
        print("\n".join(details))
        self.underline()

    def underline(self):
        print("*" * 40)

    def error(self, error_string):
        print("Error: %s" % error_string)

    def options(self):
        msg = "Make your choice..."
        return input(msg)

    def choose_lookup_string(self):
        msg = "Choose your lookup string..."
        return input(msg)

    def show_output(self, output):
        print(output)


class PriceController:
    def __init__(self):
        self.model = PriceModel()
        self.view = PriceView()
        self.start()

    def start(self):
        while True:
            choice = self.view.options()
            choice = str(choice).lower()
            if choice == "e":
                self.view.show_output("Exiting...")
                break
            if choice not in ["s", "t"]:
                self.view.error("%s is not a valid choice!" % choice)
            else:
                lookup = self.view.choose_lookup_string()
                try:
                    if choice == "s":
                        output = self.model.get_stock_code(lookup)
                    else:
                        output = self.model.get_stock_name(lookup)
                    self.view.show_output(output)
                except Exception as e:
                    self.view.error(e)
            self.view.underline()


if __name__ == "__main__":
    PriceController()