Documentation updates for urllib package. Modified the documentation for the
urllib,urllib2 -> urllib.request,urllib.error
urlparse -> urllib.parse
RobotParser -> urllib.robotparser
Updated tutorial references and other module references (http.client.rst,
ftplib.rst,contextlib.rst)
Updated the examples in the urllib2-howto
Addresses Issue3142.
diff --git a/Doc/library/urllib.parse.rst b/Doc/library/urllib.parse.rst
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+:mod:`urllib.parse` --- Parse URLs into components
+==================================================
+
+.. module:: urllib.parse
+ :synopsis: Parse URLs into or assemble them from components.
+
+
+.. index::
+ single: WWW
+ single: World Wide Web
+ single: URL
+ pair: URL; parsing
+ pair: relative; URL
+
+This module defines a standard interface to break Uniform Resource Locator (URL)
+strings up in components (addressing scheme, network location, path etc.), to
+combine the components back into a URL string, and to convert a "relative URL"
+to an absolute URL given a "base URL."
+
+The module has been designed to match the Internet RFC on Relative Uniform
+Resource Locators (and discovered a bug in an earlier draft!). It supports the
+following URL schemes: ``file``, ``ftp``, ``gopher``, ``hdl``, ``http``,
+``https``, ``imap``, ``mailto``, ``mms``, ``news``, ``nntp``, ``prospero``,
+``rsync``, ``rtsp``, ``rtspu``, ``sftp``, ``shttp``, ``sip``, ``sips``,
+``snews``, ``svn``, ``svn+ssh``, ``telnet``, ``wais``.
+
+The :mod:`urllib.parse` module defines the following functions:
+
+
+.. function:: urlparse(urlstring[, default_scheme[, allow_fragments]])
+
+ Parse a URL into six components, returning a 6-tuple. This corresponds to the
+ general structure of a URL: ``scheme://netloc/path;parameters?query#fragment``.
+ Each tuple item is a string, possibly empty. The components are not broken up in
+ smaller parts (for example, the network location is a single string), and %
+ escapes are not expanded. The delimiters as shown above are not part of the
+ result, except for a leading slash in the *path* component, which is retained if
+ present. For example:
+
+ >>> from urllib.parse import urlparse
+ >>> o = urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')
+ >>> o # doctest: +NORMALIZE_WHITESPACE
+ ParseResult(scheme='http', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
+ params='', query='', fragment='')
+ >>> o.scheme
+ 'http'
+ >>> o.port
+ 80
+ >>> o.geturl()
+ 'http://www.cwi.nl:80/%7Eguido/Python.html'
+
+ If the *default_scheme* argument is specified, it gives the default addressing
+ scheme, to be used only if the URL does not specify one. The default value for
+ this argument is the empty string.
+
+ If the *allow_fragments* argument is false, fragment identifiers are not
+ allowed, even if the URL's addressing scheme normally does support them. The
+ default value for this argument is :const:`True`.
+
+ The return value is actually an instance of a subclass of :class:`tuple`. This
+ class has the following additional read-only convenience attributes:
+
+ +------------------+-------+--------------------------+----------------------+
+ | Attribute | Index | Value | Value if not present |
+ +==================+=======+==========================+======================+
+ | :attr:`scheme` | 0 | URL scheme specifier | empty string |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`netloc` | 1 | Network location part | empty string |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`path` | 2 | Hierarchical path | empty string |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`params` | 3 | Parameters for last path | empty string |
+ | | | element | |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`query` | 4 | Query component | empty string |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`fragment` | 5 | Fragment identifier | empty string |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`username` | | User name | :const:`None` |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`password` | | Password | :const:`None` |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`hostname` | | Host name (lower case) | :const:`None` |
+ +------------------+-------+--------------------------+----------------------+
+ | :attr:`port` | | Port number as integer, | :const:`None` |
+ | | | if present | |
+ +------------------+-------+--------------------------+----------------------+
+
+ See section :ref:`urlparse-result-object` for more information on the result
+ object.
+
+
+.. function:: urlunparse(parts)
+
+ Construct a URL from a tuple as returned by ``urlparse()``. The *parts* argument
+ can be any six-item iterable. This may result in a slightly different, but
+ equivalent URL, if the URL that was parsed originally had unnecessary delimiters
+ (for example, a ? with an empty query; the RFC states that these are
+ equivalent).
+
+
+.. function:: urlsplit(urlstring[, default_scheme[, allow_fragments]])
+
+ This is similar to :func:`urlparse`, but does not split the params from the URL.
+ This should generally be used instead of :func:`urlparse` if the more recent URL
+ syntax allowing parameters to be applied to each segment of the *path* portion
+ of the URL (see :rfc:`2396`) is wanted. A separate function is needed to
+ separate the path segments and parameters. This function returns a 5-tuple:
+ (addressing scheme, network location, path, query, fragment identifier).
+
+ The return value is actually an instance of a subclass of :class:`tuple`. This
+ class has the following additional read-only convenience attributes:
+
+ +------------------+-------+-------------------------+----------------------+
+ | Attribute | Index | Value | Value if not present |
+ +==================+=======+=========================+======================+
+ | :attr:`scheme` | 0 | URL scheme specifier | empty string |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`netloc` | 1 | Network location part | empty string |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`path` | 2 | Hierarchical path | empty string |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`query` | 3 | Query component | empty string |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`fragment` | 4 | Fragment identifier | empty string |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`username` | | User name | :const:`None` |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`password` | | Password | :const:`None` |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`hostname` | | Host name (lower case) | :const:`None` |
+ +------------------+-------+-------------------------+----------------------+
+ | :attr:`port` | | Port number as integer, | :const:`None` |
+ | | | if present | |
+ +------------------+-------+-------------------------+----------------------+
+
+ See section :ref:`urlparse-result-object` for more information on the result
+ object.
+
+
+.. function:: urlunsplit(parts)
+
+ Combine the elements of a tuple as returned by :func:`urlsplit` into a complete
+ URL as a string. The *parts* argument can be any five-item iterable. This may
+ result in a slightly different, but equivalent URL, if the URL that was parsed
+ originally had unnecessary delimiters (for example, a ? with an empty query; the
+ RFC states that these are equivalent).
+
+
+.. function:: urljoin(base, url[, allow_fragments])
+
+ Construct a full ("absolute") URL by combining a "base URL" (*base*) with
+ another URL (*url*). Informally, this uses components of the base URL, in
+ particular the addressing scheme, the network location and (part of) the path,
+ to provide missing components in the relative URL. For example:
+
+ >>> from urllib.parse import urljoin
+ >>> urljoin('http://www.cwi.nl/%7Eguido/Python.html', 'FAQ.html')
+ 'http://www.cwi.nl/%7Eguido/FAQ.html'
+
+ The *allow_fragments* argument has the same meaning and default as for
+ :func:`urlparse`.
+
+ .. note::
+
+ If *url* is an absolute URL (that is, starting with ``//`` or ``scheme://``),
+ the *url*'s host name and/or scheme will be present in the result. For example:
+
+ .. doctest::
+
+ >>> urljoin('http://www.cwi.nl/%7Eguido/Python.html',
+ ... '//www.python.org/%7Eguido')
+ 'http://www.python.org/%7Eguido'
+
+ If you do not want that behavior, preprocess the *url* with :func:`urlsplit` and
+ :func:`urlunsplit`, removing possible *scheme* and *netloc* parts.
+
+
+.. function:: urldefrag(url)
+
+ If *url* contains a fragment identifier, returns a modified version of *url*
+ with no fragment identifier, and the fragment identifier as a separate string.
+ If there is no fragment identifier in *url*, returns *url* unmodified and an
+ empty string.
+
+.. function:: quote(string[, safe])
+
+ Replace special characters in *string* using the ``%xx`` escape. Letters,
+ digits, and the characters ``'_.-'`` are never quoted. The optional *safe*
+ parameter specifies additional characters that should not be quoted --- its
+ default value is ``'/'``.
+
+ Example: ``quote('/~connolly/')`` yields ``'/%7econnolly/'``.
+
+
+.. function:: quote_plus(string[, safe])
+
+ Like :func:`quote`, but also replaces spaces by plus signs, as required for
+ quoting HTML form values. Plus signs in the original string are escaped unless
+ they are included in *safe*. It also does not have *safe* default to ``'/'``.
+
+
+.. function:: unquote(string)
+
+ Replace ``%xx`` escapes by their single-character equivalent.
+
+ Example: ``unquote('/%7Econnolly/')`` yields ``'/~connolly/'``.
+
+
+.. function:: unquote_plus(string)
+
+ Like :func:`unquote`, but also replaces plus signs by spaces, as required for
+ unquoting HTML form values.
+
+
+.. function:: urlencode(query[, doseq])
+
+ Convert a mapping object or a sequence of two-element tuples to a "url-encoded"
+ string, suitable to pass to :func:`urlopen` above as the optional *data*
+ argument. This is useful to pass a dictionary of form fields to a ``POST``
+ request. The resulting string is a series of ``key=value`` pairs separated by
+ ``'&'`` characters, where both *key* and *value* are quoted using
+ :func:`quote_plus` above. If the optional parameter *doseq* is present and
+ evaluates to true, individual ``key=value`` pairs are generated for each element
+ of the sequence. When a sequence of two-element tuples is used as the *query*
+ argument, the first element of each tuple is a key and the second is a value.
+ The order of parameters in the encoded string will match the order of parameter
+ tuples in the sequence. The :mod:`cgi` module provides the functions
+ :func:`parse_qs` and :func:`parse_qsl` which are used to parse query strings
+ into Python data structures.
+
+
+.. seealso::
+
+ :rfc:`1738` - Uniform Resource Locators (URL)
+ This specifies the formal syntax and semantics of absolute URLs.
+
+ :rfc:`1808` - Relative Uniform Resource Locators
+ This Request For Comments includes the rules for joining an absolute and a
+ relative URL, including a fair number of "Abnormal Examples" which govern the
+ treatment of border cases.
+
+ :rfc:`2396` - Uniform Resource Identifiers (URI): Generic Syntax
+ Document describing the generic syntactic requirements for both Uniform Resource
+ Names (URNs) and Uniform Resource Locators (URLs).
+
+
+.. _urlparse-result-object:
+
+Results of :func:`urlparse` and :func:`urlsplit`
+------------------------------------------------
+
+The result objects from the :func:`urlparse` and :func:`urlsplit` functions are
+subclasses of the :class:`tuple` type. These subclasses add the attributes
+described in those functions, as well as provide an additional method:
+
+
+.. method:: ParseResult.geturl()
+
+ Return the re-combined version of the original URL as a string. This may differ
+ from the original URL in that the scheme will always be normalized to lower case
+ and empty components may be dropped. Specifically, empty parameters, queries,
+ and fragment identifiers will be removed.
+
+ The result of this method is a fixpoint if passed back through the original
+ parsing function:
+
+ >>> import urllib.parse
+ >>> url = 'HTTP://www.Python.org/doc/#'
+
+ >>> r1 = urllib.parse.urlsplit(url)
+ >>> r1.geturl()
+ 'http://www.Python.org/doc/'
+
+ >>> r2 = urllib.parse.urlsplit(r1.geturl())
+ >>> r2.geturl()
+ 'http://www.Python.org/doc/'
+
+
+The following classes provide the implementations of the parse results::
+
+
+.. class:: BaseResult
+
+ Base class for the concrete result classes. This provides most of the attribute
+ definitions. It does not provide a :meth:`geturl` method. It is derived from
+ :class:`tuple`, but does not override the :meth:`__init__` or :meth:`__new__`
+ methods.
+
+
+.. class:: ParseResult(scheme, netloc, path, params, query, fragment)
+
+ Concrete class for :func:`urlparse` results. The :meth:`__new__` method is
+ overridden to support checking that the right number of arguments are passed.
+
+
+.. class:: SplitResult(scheme, netloc, path, query, fragment)
+
+ Concrete class for :func:`urlsplit` results. The :meth:`__new__` method is
+ overridden to support checking that the right number of arguments are passed.
+