News feed python script

Question

The task: user-generated news feed:

1. User select what data type he wants to add

2. Provide record type required data

3. Record is published on text file in special format

Types of data:

1. News – text and city as input. Date is calculated during publishing.

2. Private ad – text and expiration date as input. Day left is calculated during publishing.

3. Your unique one with unique publish rules.

Expected result:

News -------------------------
Something happened
London, 03/01/2021 13.45
------------------------------
News -------------------------
Something other happened
Minsk, 24/01/2021 20.33
------------------------------
Private Ad ------------------
I want to sell a bike
Actual until: 01/03/2021, 21 days left
------------------------------
Joke of the day ------------
Did you hear about the claustrophobic astronaut?
He just needed a little space
Funny meter – three of ten
------------------------------

My code:

from datetime import datetime, date
from sys import exit
class Article:
 def __init__(self, title, text, line_width):
 self.title = title
 self.text = text
 self.line_width = line_width
 @staticmethod
 def publish_article(formatted_text):
 with open("all_news.txt", "a") as file:
 file.write(formatted_text)
class News(Article):
 def __init__(self, title, text, city, date, line_width):
 Article.__init__(self, title, text, line_width)
 self.city = city
 self.date = date
 def format_text(self):
 return f"{self.title}{(self.line_width - len(self.title)) * '-'}\n"\
 f"{self.text} \n"\
 f"{self.city}, {self.date.strftime('%d/%m/%Y %H:%M:%S')} \n"\
 f"{'-'*self.line_width}\n\n\n"
class Ad(Article):
 def __init__(self, title, text, end_date, line_width):
 Article.__init__(self, title, text, line_width)
 self.end_date = end_date
 def format_text(self):
 day, month, year = map(int, self.end_date.split('/'))
 days_left = (date(year, month, day) - date.today()).days
 return f"{self.title}{(self.line_width - len(self.title)) * '-'}\n"\
 f"{self.text} \n"\
 f"Actual until: {date(year, month, day).strftime('%d/%m/%Y')}, {days_left} days left \n"\
 f"{'-'*self.line_width}\n\n\n"
class PersonalNews(Article):
 def __init__(self, title, text, line_width):
 Article.__init__(self, title, text, line_width)
 def format_text(self):
 return f"{self.title}{(self.line_width - len(self.title)) * '-'}\n"\
 f"{self.text} \n"\
 f"{'-'*self.line_width}\n\n\n"
while True:
 user_input = input('Enter a number: '
 '1 - Publish news;\n'
 '2 - Publish ad; \n'
 '3 - Publish personal news\n'
 'q - Exit\n')
 if user_input == "1":
 new_news = News("News",
 input('Print your text\n'),
 input('Print city for the news\n'), datetime.now(), 30)
 new_news.publish_article(new_news.format_text())
 elif user_input == "2":
 new_news = Ad("Private Ad",
 input("Input your text\n"),
 input('Print endDate of ad in format DD/MM/YEAR\n'), 30)
 new_news.publish_article(new_news.format_text())
 elif user_input == "3":
 new_news = PersonalNews(input("Input your title\n"),
 input("Input your text\n"), 30)
 new_news.publish_article(new_news.format_text())
 elif user_input == "q":
 exit(0)
 else:
 print("Incorrect input. Please enter a number (1, 2, 3) or 'q' for exit")

Answer 1

Shadowing

Your date parameter to the constructor of News is poorly-named, because it shadows the built-in date that you've imported from datetime.

Super

Your call to Article.__init__() should use super() instead.

Data classes

Article can just be a @dataclass with its explicit __init__ removed.

Static methods

publish_article doesn't make sense as a static method. In your invocations, you're always calling format_text() on a child instance, then passing that to a static method on the parent. Instead:

• Define format_text(self) -> str: raise NotImplementedError() on Article to declare it abstract
• Change publish_article(self) to simply file.write(self.format_text())

Backslash continuation

Change this:

 return f"{self.title}{(self.line_width - len(self.title)) * '-'}\n"\
 f"{self.text} \n"\
 f"{self.city}, {self.date.strftime('%d/%m/%Y %H:%M:%S')} \n"\
 f"{'-'*self.line_width}\n\n\n"

to drop the backslashes and use parens instead:

 return (
 f"{self.title}{(self.line_width - len(self.title)) * '-'}\n"
 f"{self.text} \n"
 f"{self.city}, {self.date.strftime('%d/%m/%Y %H:%M:%S')} \n"
 f"{'-'*self.line_width}\n\n\n"
 )

Date parsing

This is evil:

 day, month, year = map(int, self.end_date.split('/'))

Instead, you should be using an actual parsing method out datetime to get you a date instance; then referring to its members. Since you're looking for DD/MM/YEAR, this will be:

end_date = datetime.strptime(self.end_date, '%d/%m/%Y').date()
# Use end_date.day, end_date.month, end_date.year

That said, if you're at all able, drop that date format like a sack of rotten potatoes. YYYY-mm-dd is sortable and unambiguous.