Re: How can i call array_length to get the length of array object?

Discussion in 'Python' started by Antoon Pardon, Jun 25, 2012.

  1. On 06/24/12 10:48, Stefan Behnel wrote:
    > gmspro, 24.06.2012 10:01:
    >
    >> Why are some methods/functions named in this way in python? __len__
    >>
    >> underscoreunderscoreNAMEunderscoreunderscore
    >>
    >> Is there any speciality of naming such methods?
    >>

    > Yes. Look up "special methods" in the documentation.
    >
    > You may have noticed the correspondence between len() and __len__(). That
    > is Python's way of allowing you to implement this kind of generic
    > functionality (sometimes referred to as a protocol).
    >
    > You also asked why len() is a function instead of a method. Don't you find
    > it much easier to use one function for everything than to look up and
    > sometimes even learn one method for each kind of object you are dealing
    > with? Python prefers simplicity here. You want the length? Use len().
    >
    > Stefan

    What does this have to do with using a function vs a method?

    In the python 2.x series, the iterator protocol, proscribe you need to
    define a "next" method, which you can call directly or which is called
    in for statements.

    Now in python 3.x the method is called "__next__" and there is a
    next-function which will call this __next__ method.

    I see no difference in difficulty between item = iter.next() and item =
    next(iter).
    Neither do I see a difference in difficulty between size = len(seq) or
    size = seq.len().

    Sure it is possible for someone feeling uncooperative to write a class
    in which method giving the length of the object was named something
    different from "len". But that is now also possible.
    Antoon Pardon, Jun 25, 2012
    #1
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Mitchua
    Replies:
    5
    Views:
    2,715
    Eric J. Roode
    Jul 17, 2003
  2. Ignacio Mondino
    Replies:
    0
    Views:
    279
    Ignacio Mondino
    Jun 24, 2012
  3. Ian Kelly
    Replies:
    0
    Views:
    220
    Ian Kelly
    Jun 24, 2012
  4. Stefan Behnel
    Replies:
    0
    Views:
    217
    Stefan Behnel
    Jun 24, 2012
  5. Mark Lawrence
    Replies:
    2
    Views:
    245
    Terry Reedy
    Jun 25, 2012
Loading...

Share This Page