GeezerVisonThe World Wide Web, restored to 800 pixels of glory. |
| Home|About|Gaming cabinet|Archives|How it works|Starter sites |
GeezerVison is showing github.com — python-patterns/patterns/creational/factory.py at master · kamyu104/python-patterns Expand file tree/ Copy pathfactory.pyMore file actions 76 lines (55 loc) · 2.08 KB / Copy pathfactory.pyFile metadata and controls76 lines (55 loc) · 2.08 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 """*What is this pattern about? A Factory is an object for creating other objects. *What does this example do? The code shows a way to localize words in two languages: English and Greek. "get_localizer" is the factory function that constructs a localizer depending on the language chosen. The localizer object will be an instance from a different class according to the language localized. However, the main code does not have to worry about which localizer will be instantiated, since the method "localize" will be called in the same way independently of the language. *Where can the pattern be used practically? The Factory Method can be seen in the popular web framework Django: https://shorturl.at/ctMPZ For example, in a contact form of a web page, the subject and the message fields are created using the same form factory (CharField()), even though they have different implementations according to their purposes. *References: http://ginstrom.com/scribbles/2007/10/08/design-patterns-python-style/ *TL;DR Creates objects without having to specify the exact class. """ class GreekLocalizer: """A simple localizer a la gettext""" def __init__(self) -> None: self.translations = {"dog": "σκύλος", "cat": "γάτα"} def localize(self, msg: str) -> str: """We'll punt if we don't have a translation""" return self.translations.get(msg, msg) class EnglishLocalizer: """Simply echoes the message""" def localize(self, msg: str) -> str: return msg def get_localizer(language: str = "English") -> object: """Factory""" localizers = { "English": EnglishLocalizer, "Greek": GreekLocalizer, } return localizers[language]() def main(): """ # Create our localizers >>> e, g = get_localizer(language="English"), get_localizer(language="Greek") # Localize some text >>> for msg in "dog parrot cat bear".split(): ... print(e.localize(msg), g.localize(msg)) dog σκύλος parrot parrot cat γάτα bear bear """ if __name__ == "__main__": import doctest doctest.testmod() |
| You are visitor 01402520 — GeezerVison does not store the pages you look up. Best viewed with Netscape Navigator 4.7 or Internet Explorer 6 at 800×600. No cookies required. |