In article <[EMAIL PROTECTED]>,
Scott David Daniels <[EMAIL PROTECTED]> wrote:
>
>This works if-and-only-if it is only in use once at a time.
>If you have multiple simultaneous accesses, you need to do
>something like:
>
> class FileReIterable2(object):
> def __init__(self, file):
> if isinstance(file, basestring):
> self.file = open(file, 'rU')
> else:
> self.file = file
> def __iter__(self):
> self.file.seek(0)
> for line in self.file:
> nextpos = self.file.tell()
> yield line
> self.file.seek(nextpos)
Hmm - I tried this with 'one.file' being just the lower case letters,
one per line:
class FileReIterable2(object):
def __init__(self, file):
if isinstance(file, basestring):
self.file = open(file, 'rU')
else:
self.file = file
def __iter__(self):
self.file.seek(0)
for line in self.file:
nextpos = self.file.tell()
yield line
self.file.seek(nextpos)
gen = FileReIterable2("one.file")
for a in gen:
for b in gen:
print " ", a.strip(), b.strip()
gen = FileReIterable2("one.file")
for a in gen:
for b in gen:
print a.strip(), b.strip()
which didn't produce lines 'a a', 'a b', etc. It produced the single
line 'a a', then stopped. A judicious proint or two showed that after
the first execution of 'for line in self.file:', the file pointer was
at EOF, not at 2, as one would expect.
Rewriting the __iter__ method to not internally iterate over the file
object, as follows, works - it now generates
a a
...
a z
b a
...
z z
class FileReIterable2(object):
def __init__(self, file):
self.file = open(file, 'rU')
def __iter__(self):
self.file.seek(0)
while True:
line = self.file.readline()
if line == '': raise StopIteration
nextpos = self.file.tell()
yield line
self.file.seek(nextpos)
--
Jim Segrave ([EMAIL PROTECTED])
--
http://mail.python.org/mailman/listinfo/python-list
