`_csv` `Reader` and `Writer` types shouldn't be directly instantiable

[chgnrdv]

The accepted way to create these objects is to use constructor functions _csv.reader() and _csv.writer() with appropriate arguments. Objects that are created through type constructors _csv.Reader and _csv.Writer turn out to be not properly initialized, and operations on them easily lead to crash:

>>> import _csv
>>> _csv.Writer().writerow([])
Segmentation fault (core dumped)

>>> import _csv
>>> list(_csv.Reader())
Segmentation fault (core dumped)

Although this is an internal detail, I'm sure that this should be fixed. I'll submit a PR shortly.
The crash appears on 3.10, 3.11 and current main.

Linked PRs

• gh-104265 Disallow instantiation of _csv.Reader and _csv.Writer #104266
• [3.11] gh-104265 Disallow instantiation of _csv.Reader and _csv.Writer (GH-104266) #104278