exception raised by nested iterator being ignored by for loop

[Raymond Hettinger]

james t kirk wrote:
> I'm writing a wrapper class to handle the line merging and filtering
> for a log file analysis app
>
> The problem I'm running into is that the StopIteration exception
> raised when the wrapped file goes past EOF isn't causing the second
> for loop to stop.

Admiral Kirk,

The innermost for-loop is catching its own StopIteration.  You need to
explicitly raise StopIteration in your next() method when there are no
more lines in the file (hint, add an else-clause to the for-loop).

Alternatively, you could simplify your life by writing the whole
wrapper as a generator:


import gzip

def wrapper(filename) :
    if filename[-3:] == ".gz" :
        fh = gzip.GzipFile(filename, "r")
    else :
        fh = open(filename, "r")
    for line in fh:
        if line[:1] != "t":     # filter out lines starting with 't'
            yield line.rstrip()
    fh.close()


Raymond Hettinger
Starfleet Command