Python: class and object-CodePudding

I have no idea why when i run my code it returns wrong value.

from __future__ import annotations


class Duration:

    def __init__(self):
        self.hours = 0
        self.days = 0
        self.weeks = 0

    def extendBy(self, hr: int) -> None:  # there is a problem
        print({self.weeks}, {self.days}, {self.hours})
        if hr   self.hours < 24:
            self.hours = hr
        if hr   self.hours > 23:
            self.hours = ((hr   self.hours) % 24)
            self.days  = int((hr - self.hours) // 24)
        if self.days > 6:
            if self.days % 7 == 0:
                self.weeks = int(self.days // 7)
                self.days = 0
            else:
                self.days = self.days % 7
                self.weeks = int(self.days // 7)
        print({self.weeks}, {self.days}, {self.hours})

These are the assertions that I use to test my code

a = Duration()
a.extendBy(25)
assert (a.weeks == 0 and a.days == 1 and a.hours == 1)
a.extendBy(24)
assert (a.weeks == 0 and a.days == 2 and a.hours == 1)
a.extendBy(7*24)
assert (a.weeks == 1 and a.days == 2 and a.hours == 1)

when i print out my code i get a correct result for weeks and hours, buts for days I always get the wrong result. If anybody know could youplease help me.

CodePudding user response：

I couldn't figure out what your logic is when reading your code, so I rewrote some of the logic while still keeping the overall structure the same:

class Duration:

    def __init__(self):
        self.hours = 0
        self.days = 0
        self.weeks = 0

    def extendBy(self, hr):
        if hr   self.hours < 24:
            self.hours  = hr
        if hr   self.hours > 23:
            self.days  = (hr   self.hours) // 24
            self.hours = (hr   self.hours) % 24
        if self.days > 6:
            self.weeks  = self.days // 7
            self.days = self.days % 7
        print(self.weeks, self.days, self.hours)

a = Duration()
a.extendBy(25)
assert (a.weeks == 0 and a.days == 1 and a.hours == 1)
a.extendBy(24)
assert (a.weeks == 0 and a.days == 2 and a.hours == 1)
a.extendBy(7*24)
assert (a.weeks == 1 and a.days == 2 and a.hours == 1)

But something like this can be written in much simpler code using divmod, try to see if you can figure it out.

CodePudding user response：

I see several issues in your code. Different issues can corrupt your data at different places. For example, your very first assignment does the wrong thing if both hr and self.hours were small (it throws away self.hours instead of adding them together).

self.hours = hr

Rather than fixing each issue, I'd suggest simplifying the code so that you don't have so many conditional cases to handle. Here's a simple approach that uses divmod (to get a divisor and remainder in a single step) and which unconditionally updates the days and weeks (though they'll often end up the same after adding zero).

def extendBy(self, hr: int) -> None:
    days, self.hours = divmod(self.hours   hr, 24)
    weeks, self.days = divmod(self.days   days, 7)
    self.weeks  = weeks