Mark Wilkinson wrote:
> Why this:
>
>> lines = iter(infile.readline, "")
>> # copy one line at a time
>> for line in lines:
>
> Rather than this?
>
>> for line in infile:
file.next() uses an internal cache. The data in that cache would be lost
when the rest of the file is copied using file.read() with
for block in iter(lambda: infile.read(BLOCKSIZE), ""):
outfile.write(block)
Demonstration:
>>> open("tmp.txt", "w").write("alpha\nbeta\ngamma\n")
>>> infile = open("tmp.txt")
>>> infile.next()
'alpha\n'
>>> infile.read()
'' # where is 'beta\ngamma\n'?
I admit I didn't profile whether the suggested approach is an overall win
over line-wise copying of the whole file or manually keeping track of the
position in the file followed by a seek().
Peter
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