[Python-checkins] Issue #11426: use 'with' statements on open files in CSV examples (original) (raw)
eli.bendersky python-checkins at python.org
Fri Mar 11 14:47:42 CET 2011
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http://hg.python.org/cpython/rev/f2a73d65422a changeset: 68369:f2a73d65422a user: Eli Bendersky <eliben at gmail.com> date: Fri Mar 11 15:47:36 2011 +0200 summary: Issue #11426: use 'with' statements on open files in CSV examples
files: Doc/library/csv.rst
diff --git a/Doc/library/csv.rst b/Doc/library/csv.rst --- a/Doc/library/csv.rst +++ b/Doc/library/csv.rst @@ -419,32 +419,36 @@ 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. @@ -453,18 +457,20 @@
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::
-- Repository URL: http://hg.python.org/cpython
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