Commit 9cc6249d authored by Eli Bendersky's avatar Eli Bendersky

Issue #11426: use 'with' statements on open files in CSV examples

parent 30178068
......@@ -400,32 +400,36 @@ Examples
The simplest example of reading a CSV file::
import csv
reader = csv.reader(open("some.csv", newline=''))
for row in reader:
print(row)
with open('some.csv', newline='') as f:
reader = csv.reader(f)
for row in reader:
print(row)
Reading a file with an alternate format::
import csv
reader = csv.reader(open("passwd"), delimiter=':', quoting=csv.QUOTE_NONE)
for row in reader:
print(row)
with open('passwd') as f:
reader = csv.reader(f, delimiter=':', quoting=csv.QUOTE_NONE)
for row in reader:
print(row)
The corresponding simplest possible writing example is::
import csv
writer = csv.writer(open("some.csv", "w"))
writer.writerows(someiterable)
with open('some.csv', 'w') as f:
writer = csv.writer(f)
writer.writerows(someiterable)
Since :func:`open` is used to open a CSV file for reading, the file
will by default be decoded into unicode using the system default
encoding (see :func:`locale.getpreferredencoding`). To decode a file
using a different encoding, use the ``encoding`` argument of open::
import csv
reader = csv.reader(open("some.csv", newline='', encoding='utf-8'))
for row in reader:
print(row)
import csv
with open('some.csv', newline='', encoding='utf-8') as f:
reader = csv.reader(f)
for row in reader:
print(row)
The same applies to writing in something other than the system default
encoding: specify the encoding argument when opening the output file.
......@@ -434,18 +438,20 @@ Registering a new dialect::
import csv
csv.register_dialect('unixpwd', delimiter=':', quoting=csv.QUOTE_NONE)
reader = csv.reader(open("passwd"), 'unixpwd')
with open('passwd') as f:
reader = csv.reader(f, 'unixpwd')
A slightly more advanced use of the reader --- catching and reporting errors::
import csv, sys
filename = "some.csv"
reader = csv.reader(open(filename, newline=''))
try:
for row in reader:
print(row)
except csv.Error as e:
sys.exit('file {}, line {}: {}'.format(filename, reader.line_num, e))
filename = 'some.csv'
with open(filename, newline='') as f:
reader = csv.reader(f)
try:
for row in reader:
print(row)
except csv.Error as e:
sys.exit('file {}, line {}: {}'.format(filename, reader.line_num, e))
And while the module doesn't directly support parsing strings, it can easily be
done::
......
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