A bug with file.tell()?
adalke at mindspring.com
Fri Sep 10 09:11:27 CEST 2004
Nick Jacobson wrote:
> Is this a bug?
[example of mixing iterator-style line reads from a
file and tell]
No, it's a documented behaviour.
] In order to make a for loop the most efficient way
] of looping over the lines of a file (a very common
] operation), the next() method uses a hidden read-ahead
] buffer. As a consequence of using a read-ahead
] buffer, combining next() with other file methods (like
] readline()) does not work right. However, using seek()
] to reposition the file to an absolute position will
] flush the read-ahead buffer.
> This code involves the file methods "seek" and "tell". Even though
> the file pointer is in the middle of the file, "tell" returns a
> position at the end of the file!
That means the underlying file handle is at
the end and everything remaining is in memory.
dalke at dalkescientific.com
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