Issue #12955: Change the urlopen() examples to use context managers where appropriate.

Patch by Martin Panter.

Issue #12955: Change the urlopen() examples to use context managers where appropriate.
Patch by Martin Panter.
556e08e9 · Berker Peksag · 48a724fa · 9575e189 · 556e08e9 · 556e08e9
Commit 556e08e9 authored Apr 12, 2015 by Berker Peksag
5 changed files
--- a/Doc/faq/library.rst
+++ b/Doc/faq/library.rst
@@ -687,7 +687,8 @@ Yes. Here's a simple example that uses urllib.request::
   ### connect and send the server a path
   req = urllib.request.urlopen('http://www.some-server.out-there'
                                '/cgi-bin/some-cgi-script', data=qs)
-   msg, hdrs = req.read(), req.info()
+   with req:
+       msg, hdrs = req.read(), req.info()

 Note that in general for percent-encoded POST operations, query strings must be
 quoted using :func:`urllib.parse.urlencode`.  For example, to send

--- a/Doc/howto/urllib2.rst
+++ b/Doc/howto/urllib2.rst
@@ -53,8 +53,8 @@ Fetching URLs
 The simplest way to use urllib.request is as follows::

    import urllib.request
-    response = urllib.request.urlopen('http://python.org/')
-    html = response.read()
+    with urllib.request.urlopen('http://python.org/') as response:
+       html = response.read()

 If you wish to retrieve a resource via URL and store it in a temporary location,
 you can do so via the :func:`~urllib.request.urlretrieve` function::
@@ -79,8 +79,8 @@ response::
    import urllib.request

    req = urllib.request.Request('http://www.voidspace.org.uk')
-    response = urllib.request.urlopen(req)
-    the_page = response.read()
+    with urllib.request.urlopen(req) as response:
+       the_page = response.read()

 Note that urllib.request makes use of the same Request interface to handle all URL
 schemes.  For example, you can make an FTP request like so::
@@ -117,8 +117,8 @@ library. ::
    data = urllib.parse.urlencode(values)
    data = data.encode('utf-8') # data should be bytes
    req = urllib.request.Request(url, data)
-    response = urllib.request.urlopen(req)
-    the_page = response.read()
+    with urllib.request.urlopen(req) as response:
+       the_page = response.read()

 Note that other encodings are sometimes required (e.g. for file upload from HTML
 forms - see `HTML Specification, Form Submission
@@ -183,8 +183,8 @@ Explorer [#]_. ::
    data  = urllib.parse.urlencode(values)
    data = data.encode('utf-8')
    req = urllib.request.Request(url, data, headers)
-    response = urllib.request.urlopen(req)
-    the_page = response.read()
+    with urllib.request.urlopen(req) as response:
+       the_page = response.read()

 The response also has two useful methods. See the section on `info and geturl`_
 which comes after we have a look at what happens when things go wrong.

--- a/Doc/library/concurrent.futures.rst
+++ b/Doc/library/concurrent.futures.rst
@@ -155,8 +155,8 @@ ThreadPoolExecutor Example

   # Retrieve a single page and report the url and contents
   def load_url(url, timeout):
-       conn = urllib.request.urlopen(url, timeout=timeout)
-       return conn.readall()
+       with urllib.request.urlopen(url, timeout=timeout) as conn:
+           return conn.read()

   # We can use a with statement to ensure threads are cleaned up promptly
   with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:

--- a/Doc/library/urllib.request.rst
+++ b/Doc/library/urllib.request.rst
@@ -1060,8 +1060,9 @@ This example gets the python.org main page and displays the first 300 bytes of
 it. ::

   >>> import urllib.request
-   >>> f = urllib.request.urlopen('http://www.python.org/')
-   >>> print(f.read(300))
+   >>> with urllib.request.urlopen('http://www.python.org/') as f:
+   ...     print(f.read(300))
+   ...
   b'<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">\n\n\n<html
   xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">\n\n<head>\n
@@ -1103,8 +1104,9 @@ when the Python installation supports SSL. ::
   >>> import urllib.request
   >>> req = urllib.request.Request(url='https://localhost/cgi-bin/test.cgi',
   ...                       data=b'This data is passed to stdin of the CGI')
-   >>> f = urllib.request.urlopen(req)
-   >>> print(f.read().decode('utf-8'))
+   >>> with urllib.request.urlopen(req) as f:
+   ...     print(f.read().decode('utf-8'))
+   ...
   Got Data: "This data is passed to stdin of the CGI"

 The code for the sample CGI used in the above example is::
@@ -1119,7 +1121,8 @@ Here is an example of doing a ``PUT`` request using :class:`Request`::
    import urllib.request
    DATA=b'some data'
    req = urllib.request.Request(url='http://localhost:8080', data=DATA,method='PUT')
-    f = urllib.request.urlopen(req)
+    with urllib.request.urlopen(req) as f:
+        pass
    print(f.status)
    print(f.reason)

@@ -1185,8 +1188,10 @@ containing parameters::
   >>> import urllib.request
   >>> import urllib.parse
   >>> params = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
-   >>> f = urllib.request.urlopen("http://www.musi-cal.com/cgi-bin/query?%s" % params)
-   >>> print(f.read().decode('utf-8'))
+   >>> url = "http://www.musi-cal.com/cgi-bin/query?%s" % params
+   >>> with urllib.request.urlopen(url) as f:
+   ...     print(f.read().decode('utf-8'))
+   ...

 The following example uses the ``POST`` method instead. Note that params output
 from urlencode is encoded to bytes before it is sent to urlopen as data::
@@ -1198,8 +1203,9 @@ from urlencode is encoded to bytes before it is sent to urlopen as data::
   >>> request = urllib.request.Request("http://requestb.in/xrbl82xr")
   >>> # adding charset parameter to the Content-Type header.
   >>> request.add_header("Content-Type","application/x-www-form-urlencoded;charset=utf-8")
-   >>> f = urllib.request.urlopen(request, data)
-   >>> print(f.read().decode('utf-8'))
+   >>> with urllib.request.urlopen(request, data) as f:
+   ...     print(f.read().decode('utf-8'))
+   ...

 The following example uses an explicitly specified HTTP proxy, overriding
 environment settings::
@@ -1207,15 +1213,17 @@ environment settings::
   >>> import urllib.request
   >>> proxies = {'http': 'http://proxy.example.com:8080/'}
   >>> opener = urllib.request.FancyURLopener(proxies)
-   >>> f = opener.open("http://www.python.org")
-   >>> f.read().decode('utf-8')
+   >>> with opener.open("http://www.python.org") as f:
+   ...     f.read().decode('utf-8')
+   ...

 The following example uses no proxies at all, overriding environment settings::

   >>> import urllib.request
   >>> opener = urllib.request.FancyURLopener({})
-   >>> f = opener.open("http://www.python.org/")
-   >>> f.read().decode('utf-8')
+   >>> with opener.open("http://www.python.org/") as f:
+   ...     f.read().decode('utf-8')
+   ...


 Legacy interface

--- a/Doc/tutorial/stdlib.rst
+++ b/Doc/tutorial/stdlib.rst
@@ -153,10 +153,11 @@ protocols. Two of the simplest are :mod:`urllib.request` for retrieving data
 from URLs and :mod:`smtplib` for sending mail::

   >>> from urllib.request import urlopen
-   >>> for line in urlopen('http://tycho.usno.navy.mil/cgi-bin/timer.pl'):
-   ...     line = line.decode('utf-8')  # Decoding the binary data to text.
-   ...     if 'EST' in line or 'EDT' in line:  # look for Eastern Time
-   ...         print(line)
+   >>> with urlopen('http://tycho.usno.navy.mil/cgi-bin/timer.pl') as response:
+   ...     for line in response:
+   ...         line = line.decode('utf-8')  # Decoding the binary data to text.
+   ...         if 'EST' in line or 'EDT' in line:  # look for Eastern Time
+   ...             print(line)

   <BR>Nov. 25, 09:43:32 PM EST