Every month, your partner meets up with their best friend. Both of them have very busy schedules, making it challenging to find a suitable date! Given your own busy schedule, your partner always double-checks potential meetup dates with you:
In this month's call, your partner asked you this question:
Confused, you ask what a "teenth" day is. Your partner explains that a teenth day, a concept they made up, refers to the days in a month that end in '-teenth':
As there are also seven weekdays, it is guaranteed that each day of the week has exactly one teenth day each month.
Now that you understand the concept of a teenth day, you check your calendar. You don't have anything planned on the teenth Thursday, so you happily confirm the date with your partner.
Your task is to find the exact date of a meetup, given a month, year, weekday and week.
There are five week values to consider: first, second, third, fourth, last, teenth.
For example, you might be asked to find the date for the meetup on the first Monday in January 2018 (January 1, 2018).
Similarly, you might be asked to find:
The teenth week refers to the seven days in a month that end in '-teenth' (13th, 14th, 15th, 16th, 17th, 18th and 19th).
If asked to find the teenth Saturday of August, 1953, we check its calendar:
August 1953
Su Mo Tu We Th Fr Sa
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
From this we find that the teenth Saturday is August 15, 1953.
We have added an additional week descriptor (fifth) for the fifth weekday of the month, if there is one.
If there is not a fifth weekday in a month, you should raise an exception.
Sometimes it is necessary to both customize and raise exceptions in your code. When you do this, you should always include a meaningful error message to indicate what the source of the error is. This makes your code more readable and helps significantly with debugging.
Custom exceptions can be created through new exception classes (see classes for more detail.) that are typically subclasses of Exception.
For situations where you know the error source will be a derivative of a certain exception type, you can choose to inherit from one of the built in error types under the Exception class. When raising the error, you should still include a meaningful message.
This particular exercise requires that you create a custom exception to be raised/"thrown" when your meetup() function is given a weekday name and number combination that is invalid. The tests will only pass if you customize appropriate exceptions, raise those exceptions, and include appropriate error messages.
To customize a built-in exception, create a class that inherits from that exception. When raising the custom exception with a message, write the message as an argument to the exception type:
# subclassing the built-in ValueError to create MeetupDayException
class MeetupDayException(ValueError):
"""Exception raised when the Meetup weekday and count do not result in a valid date.
message: explanation of the error.
"""
def __init__(self, message):
self.message = message
# raising a MeetupDayException
raise MeetupDayException("That day does not exist.")
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