Re: Can one get "for x in y" to work for non builtin classes?
On Mon, 03 Mar 2008 12:17:39 +0100, M.-A. Lemburg wrote: > It's also possible to implement .__getitem__() and .__len__() > methods and have Python create an iterator on-the-fly. That's > how Python used to work before iterators were added to the > language. A suitable `__getitem__()` is enough. The end will be signaled by an `IndexError`. Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
Re: Can one get "for x in y" to work for non builtin classes?
On 2008-03-02 15:06, Preben Randhol wrote:
> Hi
>
> I'm making a kind of ordered dictionary class. It is not exactly a
> dictionary, but it uses a list and dictionary to store the data.
>
> Something like:
>
> class dbase(list):
> '''Database class keeping track of the order and data'''
>
> def __init__(self):
> self.__data = {}
> self.__order = []
> self.__uniq_id = 0
>
> I'm just wondering if it is possible to get my class to work so that if
> one do:
>
>
> d=dbase()
> d.append("Data")
> d.append([1,2])
>
> one can do like this to iterate over the data.
>
> for x in d:
> ...
>
> I'm looking at the list class but I don't quite understand from pydoc
> which __ __ methods I have to implement to get the above to work.
The easiest is to implement an iterator which then get's
returned by the .__iter__() method.
http://www.python.org/doc/lib/typeiter.html
It's also possible to implement .__getitem__() and .__len__()
methods and have Python create an iterator on-the-fly. That's
how Python used to work before iterators were added to the
language.
--
Marc-Andre Lemburg
eGenix.com
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Re: Can one get "for x in y" to work for non builtin classes?
On Sun, 2 Mar 2008 06:15:54 -0800 (PST) Giles Brown <[EMAIL PROTECTED]> wrote: > http://docs.python.org/lib/typeiter.html Thanks! -- http://mail.python.org/mailman/listinfo/python-list
Re: Can one get "for x in y" to work for non builtin classes?
On Sun, 2 Mar 2008 08:09:24 -0800 (PST) [EMAIL PROTECTED] wrote: > On Mar 2, 8:15 am, Giles Brown <[EMAIL PROTECTED]> wrote: > > http://docs.python.org/lib/typeiter.html > > Be careful on your descision to return an ordered iterator or not-- > that is, whether it iterates over the dictionary or the list (if I > understand you correctly). If the order's unimportant then please > disregard. I was thinking to iterate over the list which contains the uniq_ids as order is important :-) Thanks! Preben -- http://mail.python.org/mailman/listinfo/python-list
Re: Can one get "for x in y" to work for non builtin classes?
On Mar 2, 8:15 am, Giles Brown <[EMAIL PROTECTED]> wrote: > On Mar 2, 2:08 pm, Preben Randhol > [EMAIL PROTECTED]> wrote: > > On Sun, 2 Mar 2008 15:06:17 +0100 > > > Preben Randhol <[EMAIL PROTECTED]> wrote: > > > class dbase(list): > > > Sorry the definition of the class is: > > > class dbase(object): > > > it doesn't derive from the list class. > > > Preben > > http://docs.python.org/lib/typeiter.html Be careful on your descision to return an ordered iterator or not-- that is, whether it iterates over the dictionary or the list (if I understand you correctly). If the order's unimportant then please disregard. You can also use: >>> a= [2,3,4] >>> b= iter( a ) >>> next( b ) 2 >>> next( b ) 3 >>> next( b ) 4 -- http://mail.python.org/mailman/listinfo/python-list
Re: Can one get "for x in y" to work for non builtin classes?
On Mar 2, 2:08 pm, Preben Randhol wrote: > On Sun, 2 Mar 2008 15:06:17 +0100 > > Preben Randhol <[EMAIL PROTECTED]> wrote: > >class dbase(list): > > Sorry the definition of the class is: > > class dbase(object): > > it doesn't derive from the list class. > > Preben http://docs.python.org/lib/typeiter.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Can one get "for x in y" to work for non builtin classes?
On Sun, 2 Mar 2008 15:06:17 +0100 Preben Randhol <[EMAIL PROTECTED]> wrote: > class dbase(list): Sorry the definition of the class is: class dbase(object): it doesn't derive from the list class. Preben -- http://mail.python.org/mailman/listinfo/python-list
