Pagination: Give the InvalidPage exception an attribute storing the converted integer number

[miracle2k]

This truly is a tiny issue, but when subclassing Paginator, if you override page(), there are different things that can happen:

1. Page number is valid, you get a Page object.
2. Page number is out of range, InvalidPage is raised
3. Page number is not a number, InvalidPage is raised

In your child class, you cannot differ between 1) and 2/3), so if you want to work with "number" afterwards, you once again need to check it's an int, and raise the appropriate exceptions if not.

Suggestioned solution: Give the InvalidPage exception a number field that is set whenever the number was successfully converted to an integer.

Example:

class MyPaginator(Pagintor):
   def page(self, number):
      try:
          super(MyPaginator, self).page(number)
      except InvalidPage, e:
          # using "number" here is problematic - it might be a string
          if e.number > self.num_pages:
             # ...

[Adrian Holovaty]

(In [7867]) Fixed #7307 -- Split InvalidPage exception into two subclasses, PageNotAnInteger and EmptyPage, for granular exception catching. Thanks for the idea, miracle2k