Frankenstring

[Peter Otten]

Thomas Lotze wrote:

> I think I need an iterator over a string of characters pulling them out
> one by one, like a usual iterator over a str does. At the same time the
> thing should allow seeking and telling like a file-like object:

>>> from StringIO import StringIO
>>> class frankenstring(StringIO):
...     def next(self):
...             c = self.read(1)
...             if not c:
...                     raise StopIteration
...             return c
...
>>> f = frankenfile("0123456789")
>>> for c in f:
...     print c
...     if c == "2":
...             break
...
0
1
2
>>> f.tell()
3
>>> f.seek(7)
>>> for c in f:
...     print c
...
7
8
9
>>>

A non-intrusive alternative:

>>> def chariter(instream):
...     def char(): return instream.read(1)
...     return iter(char, "")
...
>>> f = StringIO("0123456789")
>>> for c in chariter(f):
...     print c
...     if c == "2": break
...
0
1
2
>>> f.tell()
3

Performance is probably not so good, but if you really want to do it in C,
with cStringIO you might be /almost/ there.

Peter