[Python-ideas] Add peekline(), peeklines(n) and optional maxlines argument to readlines()

[Giampaolo Rodolà]

Whops!
In my peekline examples obviously f.peeklines must be replaced with
f.readlines.
=)


Regards,

--- Giampaolo
http://code.google.com/p/pyftpdlib/
http://code.google.com/p/psutil/ <http://code.google.com/p/pyftpdlib/>

2011/9/30 Giampaolo Rodolà <g.rodola at gmail.com>

> +0.5 about f.readlines(maxlines=10); it might be a good addition since the
> sizehint parameter does not allow an actual prediction of how many lines
> will be returned.
> On the other side the two arguments are mutually exclusive, therefore I'm
> not sure what expect in case both are specified (maybe ValueError, but such
> kind of APIs always leave me a little skeptical).
> +0 about f.peeklines(10) as it only saves one line of code:
>
> f.peeklines(10)
> f.seek(0)
>
> ...or 2 in case you're not at the beginning of the file.
>
> before = f.tell()
> f.peeklines(10)
> f.seek(before)
>
> Not a great advantage vs. the fact of introducing (and remembering) a new
> function, in my opinion.
>
> Regards,
>
> --- Giampaolo
> http://code.google.com/p/pyftpdlib/
> http://code.google.com/p/psutil/ <http://code.google.com/p/pyftpdlib/>
>
> 2011/9/30 John O'Connor <jxo6948 at rit.edu>
>
>> It seems there could be a cleaner way of reading the first n lines of
>> a file and additionally not seeking past those lines (ie peek). This
>> is obviously a trivial task for 1 line ie...
>> f.readline()
>> f.seek(0)
>> but one that I think would make sense to add to the IO implementation,
>> given that we already have readline, readlines, and peek I think
>> peekline() or peeklines(n) is only a natural addition. The argument
>> for doing so (in 3.3 of course), is primarily readability but also
>> that the maintenance burden *seems* like it would be low. This
>> addition would also be helpful and more concise where n > 1.
>>
>> I think readlines() should also take an optional argument for a max
>> number of lines to read. It seems more common/helpful to me than
>> 'hint' for max bytes. In n>1 case one could do...
>>
>> f.readlines(maxlines=10)
>>
>> or for the 'peek' case
>>
>> f.peeklines(10)
>>
>>
>> I also didn't find any of the answers from
>>
>> http://stackoverflow.com/questions/1767513/read-first-n-lines-of-a-file-in-python
>> to be very compelling.
>>
>> I am more than willing to propose a patch if the idea(s) are supported.
>>
>> - John
>> _______________________________________________
>> Python-ideas mailing list
>> Python-ideas at python.org
>> http://mail.python.org/mailman/listinfo/python-ideas
>>
>
>
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