python - 有什么办法可以改进这个Python函数吗？

Question

def __number():
    # This line returns the number of the latest created object
    # as a "Factura" object in format "n/year"
    last = Factura.objects.filter(f_type__exact=False).latest('number')

    # We convert it into a string and split it to get only the first number
    spl = str(last).split('/')[0]

    # Convert it into integer so we can do math
    n = int(spl)

    # Get the current year
    y = date.today().strftime('%y')

    # If none return 1/year
    if n == None:
        return str(1) + '/' + str(y)

    # Else we increment the number in one.
    else:
        n = n + 1
        return str(n) + '/' + str(y)

它的作用:它自动生成一个格式为“1/year”“2/year”等的数字。如果用户输入其他数字，例如564/10 函数紧随其后，下一个函数将是 565/10。

即使用户介绍了 p.e. 34/10 在输入 564/10 后，函数将遵循最大的数字。

我这样做对吗还是有更好的方法？

<小时/>

更新:

def __number():
    current_year = date.today().strftime('%y')
    try:
        facturas_emmited = Factura.objects.filter(f_type__exact=False)
        latest_object = facturas_emmited.latest('number').__str__()
        first_number = int(latest_object.split("/")[0]) + 1
    except Factura.DoesNotExist:
        first_number = 1
    return '%s/%s' % (first_number, current_year)

Answer 1

这实际上只是一个开始，但我首先用自记录代码替换一些注释。

def __number():
    # "Factura" object in format "n/year"
    latest_object = Factura.objects.filter(f_type__exact=False).latest('number')

    # Better name can be available if you explain why the first number is important and what it means
    # Do Factura objects not have a __repr__ or __str__ method that you must cast it?
    first_number = int(str(latest_object).split('/')[0])
    current_year = date.today().strftime('%y')
    # Use "is None" rather than "== None"
    if first_number is None:
        return '1/%d' % current_year
    # No else needed because of return above
    # Why do we add 1 to first number? Comments should explain _why_, not how
    return '%d/%d' % (first_number + 1, current_year)