Re: [Python-Dev] [Csv] skipfinalspace
On Mon, Oct 20, 2008 at 00:48, John Machin
Tom Brown wrote:
(Continuing thread started at http://mail.python.org/pipermail/csv/2008-October/000688.html)
On Sun, Oct 19, 2008 at 16:46, Andrew McNamara < andrewm@object-craft.com.au mailto:andrewm@object-craft.com.au> wrote:
>I downloaded the 2.6 source tar ball, but is it too late for new features to >get into versions <3?
Yep.
>How would you feel about adding the following tests to Lib/test/test_csv.py >and getting them to pass? > >Also http://www.python.org/doc/2.5.2/lib/csv-fmt-params.html says >"*skipinitialspace *When True, whitespace immediately following the >delimiter is ignored." >but my tests show whitespace at the start of any field is ignored, including >the first field.
I suspect (but I haven't checked) that it means "after the delimiter and before any quoted field (or some variation on that).
I agree that whitespace after the delimiter and before any quoted field is skipped. Also whitespace after the start of the line and before any quoted field is skipped.
All of the "dialect" parameters are there to allow parsing of a
specific common form of CSV file. Because there is no formal definition of the format, the module simply aims to parse (and produce the same result) as common applications such as Excel and Access. Changing the behaviour in any non-backwards compatible way is sure to get screams of anguish from many users. Even when the behaviour appears to be a bug, you can be sure people are counting on it working like that.
skipinitialspace defaults to false and by the same logic skipfinalspace should default to false to preserve compatibility with the csv module in 2.6. On the other hand, the switch to version 3 is as good a time as any to break backwards compatibility to adopt something that works better for new users.
Read Andrew's lips: They don't want "better", they want "the same as MS".
okay.
Based on my experience parsing several hundred csv generated by many
different people I think it would be nice to at least have a dialect that is excel + skipinitialspace=True + skipfinalspace=True.
Based on my experience extracting data from innumerable csv files (and infinite varieties thereof),
Wow, that is a _lot_ of files :-P spreadsheet files, and database tables, in 99.99% of cases one should
automatically apply the following transformations to each text field: * strip leading whitespace * strip trailing whitespace * replace embedded runs of whitespace by a single space and one needs to ensure that the definition of whitespace includes the no-break space (NBSP) character.
As this "space normalisation" is needed for all input sources, the csv module is IMHO the wrong place to put it. A string method would be a better idea.
I agree that strip() and something like re.sub(r"\s+", " " are handy. If 99.99% percent of csv readers should be applying these fixes to every field perhaps there should be easy-to-enable option to apply it. Why force almost everyone to discover they need the transformations and put a line of code around csv reader?
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Tom Brown