Question

i don’t know “self._iterator = iter(self._container)”in next code.

in django.http :

class HttpResponse(object):
    def __iter__(self):
        self._iterator = iter(self._container)
        return self

    def next(self):
        chunk = self._iterator.next()
        if isinstance(chunk, unicode):
            chunk = chunk.encode(self._charset)
        return str(chunk)

i read the api :

Return an iterator object. The first
argument is interpreted very
differently depending on the presence
of the second argument. Without a
second argument, o must be a
collection object which supports the
iteration protocol (the __iter__()
method), or it must support the
sequence protocol (the __getitem__()
method with integer arguments starting
at 0). If it does not support either
of those protocols, TypeError is
raised. If the second argument,
sentinel, is given, then o must be a
callable object. The iterator created
in this case will call o with no
arguments for each call to its next()
method; if the value returned is equal
to sentinel, StopIteration will be
raised, otherwise the value will be
returned. One useful application of
the second form of iter() is to read
lines of a file until a certain line
is reached. The following example
reads a file until “STOP” is reached:

but i also don’t know what the iter function made .

i know the __iter__:
class a(object):
    def __init__(self,x=10):
        self.x = x
    def __iter__(self):
        return self
    def next(self):
        if self.x > 0:
                self.x-=1
                return self.x
        else:
                raise StopIteration

Please try to use the code, rather than text, because my English is not very good, thank you

Answer 1

An iterator can be iterated:

for item in mylist:
    print item

for key,item in enumerate(mylist):
    print key,":",item

for i in range(0,50):
    print i

To use for item in X, X must be iterable.

You can make your class iterable by adding next(self) etc, as in your sample. So with

class a(object):
    def __init__(self,x=10):
        self.x = x
    def __iter__(self):
        return self
    def next(self):
        if self.x > 0:
            self.x-=1
            return self.x
        else:
            raise StopIteration

Then you can do

 ainst = a()
 for item in aisnt:
     print item