[issue20028] Confusing error message when giving invalid quotechar in initializing csv dialect

[Vajrasky Kok]

New submission from Vajrasky Kok:

Python 3.4.0b1 (default:13a505260f17, Dec 20 2013, 12:02:44) 
[GCC 4.7.2] on linux
>>> import _csv
>>> import csv
>>> _csv.Dialect(quotechar=b'+')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: "quotechar" must be string, not bytes

Hey, that's not true. Quotechar can be None.

>>> _csv.Dialect(quotechar=None)
<_csv.Dialect object at 0x7f64a8534790>

>>> _csv.Dialect(quotechar="cutecat")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: "quotechar" must be an 1-character string

That's not strictly true. Quotechar can be 0-character string in certain situation.

>>> _csv.Dialect(quotechar="", quoting=csv.QUOTE_NONE)
<_csv.Dialect object at 0x7f64a85345f0>

Python 2.7 suffers the same issue.

----------
components: Library (Lib)
messages: 206663
nosy: r.david.murray, serhiy.storchaka, vajrasky
priority: normal
severity: normal
status: open
title: Confusing error message when giving invalid quotechar in initializing csv dialect
type: behavior
versions: Python 2.7, Python 3.3, Python 3.4

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue20028>
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