csv and mixed lists of unicode and numbers

[Peter Otten]

Sibylle Koczian wrote:

> This problem really goes away with Python 3 (tried it on another
> machine), but something else changes too: in Python 2.6 the
> documentation for the csv module explicitly says "If csvfile is a file
> object, it must be opened with the ‘b’ flag on platforms where that
> makes a difference." The documentation for Python 3.1 doesn't have this
> sentence, and if I do that in Python 3.1 I get for all sorts of data,
> even for a list with only one integer literal:
> 
> TypeError: must be bytes or buffer, not str

Read the documentation for open() at

http://docs.python.org/3.1/library/functions.html#open

There are significant changes with respect to 2.x; you won't even get a file 
object anymore:

>>> open("tmp.txt", "w")
<_io.TextIOWrapper name='tmp.txt' encoding='UTF-8'>
>>> _.write("yadda")
5
>>> open("tmp.dat", "wb")
<_io.BufferedWriter name='tmp.dat'>
>>> _.write("yadda")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: write() argument 1 must be bytes or buffer, not str
>>> open("tmp.dat", "wb").write(b"yadda")
5

If you specify the "b" flag in 3.x the write() method expects bytes, not 
str. The translation of newlines is now controlled by the "newline" 
argument.

Peter