[Csv] Re: First Cut at CSV PEP

[Dave Cole]

>>>>> "Kevin" == Kevin Altis <altis at semi-retired.com> writes:

>> Exceptions should be raised for anything else, even None.  An empty
>> field is "".

[snip]

>> I really still dislike this whole None thing.  Whose use case is
>> that anyway?

[snip]

Kevin> Are you saying that you want to throw an exception instead?
Kevin> Booleans may also present a problem. I was mostly thinking in
Kevin> terms of importing and exporting data from embedded databases
Kevin> like MetaKit, my own list of dictionaries (flatfile stuff),
Kevin> PySQLite, Gadfly. Anyway, the implication might be that it is
Kevin> necessary for the user to sanitize data as part of the export
Kevin> operation too. Have to ponder that.

The penny finally dropped!!!

The None thing and the implicit __str__ conversion is there in the
Object Craft parser to be compatible with the DB-API.  Consider the
following code (which is close to something I had to do a couple of
years ago):

    import csv
    import Sybase

    db = Sybase.connect(server, user, passwd, database)
    c = db.cursor()
    c.execute('select some stuff from the database')

    p = csv.parser()
    fp = open('results.csv', 'w')
    for row in c.fetchall():
        fp.write(p.join(row))
        fp.write('\n')

We would be doing it slightly better now:

    import csv
    import Sybase

    db = Sybase.connect(server, user, passwd, database)
    c = db.cursor()
    c.execute('select some stuff from the database')

    csvwriter = csv.writer(file('results.csv', 'w'))
    for row in c.fetchall():
        csvwriter.write(row)

Or even:

    import csv
    import Sybase

    db = Sybase.connect(server, user, passwd, database)
    c = db.cursor()
    c.execute('select some stuff from the database')

    csvwriter = csv.writer(file('results.csv', 'w'))
    csvwriter.writelines(c)

Now without the implicit __str__ and conversion of None to '' we would
require a shirtload of code to do the same thing, only it would be as
slow as a slug on valium.

- Dave

-- 
http://www.object-craft.com.au