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diff --git a/sys/src/cmd/python/Doc/lib/liburllib.tex b/sys/src/cmd/python/Doc/lib/liburllib.tex deleted file mode 100644 index 75ee310d5..000000000 --- a/sys/src/cmd/python/Doc/lib/liburllib.tex +++ /dev/null @@ -1,497 +0,0 @@ -\section{\module{urllib} --- - Open arbitrary resources by URL} - -\declaremodule{standard}{urllib} -\modulesynopsis{Open an arbitrary network resource by URL (requires sockets).} - -\index{WWW} -\index{World Wide Web} -\index{URL} - - -This module provides a high-level interface for fetching data across -the World Wide Web. In particular, the \function{urlopen()} function -is similar to the built-in function \function{open()}, but accepts -Universal Resource Locators (URLs) instead of filenames. Some -restrictions apply --- it can only open URLs for reading, and no seek -operations are available. - -It defines the following public functions: - -\begin{funcdesc}{urlopen}{url\optional{, data\optional{, proxies}}} -Open a network object denoted by a URL for reading. If the URL does -not have a scheme identifier, or if it has \file{file:} as its scheme -identifier, this opens a local file (without universal newlines); -otherwise it opens a socket to a server somewhere on the network. If -the connection cannot be made -the \exception{IOError} exception is raised. If all went well, a -file-like object is returned. This supports the following methods: -\method{read()}, \method{readline()}, \method{readlines()}, \method{fileno()}, -\method{close()}, \method{info()} and \method{geturl()}. It also has -proper support for the iterator protocol. -One caveat: the \method{read()} method, if the size argument is -omitted or negative, may not read until the end of the data stream; -there is no good way to determine that the entire stream from a socket -has been read in the general case. - -Except for the \method{info()} and \method{geturl()} methods, -these methods have the same interface as for -file objects --- see section \ref{bltin-file-objects} in this -manual. (It is not a built-in file object, however, so it can't be -used at those few places where a true built-in file object is -required.) - -The \method{info()} method returns an instance of the class -\class{mimetools.Message} containing meta-information associated -with the URL. When the method is HTTP, these headers are those -returned by the server at the head of the retrieved HTML page -(including Content-Length and Content-Type). When the method is FTP, -a Content-Length header will be present if (as is now usual) the -server passed back a file length in response to the FTP retrieval -request. A Content-Type header will be present if the MIME type can -be guessed. When the method is local-file, returned headers will include -a Date representing the file's last-modified time, a Content-Length -giving file size, and a Content-Type containing a guess at the file's -type. See also the description of the -\refmodule{mimetools}\refstmodindex{mimetools} module. - -The \method{geturl()} method returns the real URL of the page. In -some cases, the HTTP server redirects a client to another URL. The -\function{urlopen()} function handles this transparently, but in some -cases the caller needs to know which URL the client was redirected -to. The \method{geturl()} method can be used to get at this -redirected URL. - -If the \var{url} uses the \file{http:} scheme identifier, the optional -\var{data} argument may be given to specify a \code{POST} request -(normally the request type is \code{GET}). The \var{data} argument -must be in standard \mimetype{application/x-www-form-urlencoded} format; -see the \function{urlencode()} function below. - -The \function{urlopen()} function works transparently with proxies -which do not require authentication. In a \UNIX{} or Windows -environment, set the \envvar{http_proxy}, \envvar{ftp_proxy} or -\envvar{gopher_proxy} environment variables to a URL that identifies -the proxy server before starting the Python interpreter. For example -(the \character{\%} is the command prompt): - -\begin{verbatim} -% http_proxy="http://www.someproxy.com:3128" -% export http_proxy -% python -... -\end{verbatim} - -In a Windows environment, if no proxy environment variables are set, -proxy settings are obtained from the registry's Internet Settings -section. - -In a Macintosh environment, \function{urlopen()} will retrieve proxy -information from Internet\index{Internet Config} Config. - -Alternatively, the optional \var{proxies} argument may be used to -explicitly specify proxies. It must be a dictionary mapping scheme -names to proxy URLs, where an empty dictionary causes no proxies to be -used, and \code{None} (the default value) causes environmental proxy -settings to be used as discussed above. For example: - -\begin{verbatim} -# Use http://www.someproxy.com:3128 for http proxying -proxies = {'http': 'http://www.someproxy.com:3128'} -filehandle = urllib.urlopen(some_url, proxies=proxies) -# Don't use any proxies -filehandle = urllib.urlopen(some_url, proxies={}) -# Use proxies from environment - both versions are equivalent -filehandle = urllib.urlopen(some_url, proxies=None) -filehandle = urllib.urlopen(some_url) -\end{verbatim} - -The \function{urlopen()} function does not support explicit proxy -specification. If you need to override environmental proxy settings, -use \class{URLopener}, or a subclass such as \class{FancyURLopener}. - -Proxies which require authentication for use are not currently -supported; this is considered an implementation limitation. - -\versionchanged[Added the \var{proxies} support]{2.3} -\end{funcdesc} - -\begin{funcdesc}{urlretrieve}{url\optional{, filename\optional{, - reporthook\optional{, data}}}} -Copy a network object denoted by a URL to a local file, if necessary. -If the URL points to a local file, or a valid cached copy of the -object exists, the object is not copied. Return a tuple -\code{(\var{filename}, \var{headers})} where \var{filename} is the -local file name under which the object can be found, and \var{headers} -is whatever the \method{info()} method of the object returned by -\function{urlopen()} returned (for a remote object, possibly cached). -Exceptions are the same as for \function{urlopen()}. - -The second argument, if present, specifies the file location to copy -to (if absent, the location will be a tempfile with a generated name). -The third argument, if present, is a hook function that will be called -once on establishment of the network connection and once after each -block read thereafter. The hook will be passed three arguments; a -count of blocks transferred so far, a block size in bytes, and the -total size of the file. The third argument may be \code{-1} on older -FTP servers which do not return a file size in response to a retrieval -request. - -If the \var{url} uses the \file{http:} scheme identifier, the optional -\var{data} argument may be given to specify a \code{POST} request -(normally the request type is \code{GET}). The \var{data} argument -must in standard \mimetype{application/x-www-form-urlencoded} format; -see the \function{urlencode()} function below. - -\versionchanged[ -\function{urlretrieve()} will raise \exception{ContentTooShortError} -when it detects that the amount of data available -was less than the expected amount (which is the size reported by a -\var{Content-Length} header). This can occur, for example, when the -download is interrupted. - -The \var{Content-Length} is treated as a lower bound: if there's more data -to read, urlretrieve reads more data, but if less data is available, -it raises the exception. - -You can still retrieve the downloaded data in this case, it is stored -in the \member{content} attribute of the exception instance. - -If no \var{Content-Length} header was supplied, urlretrieve can -not check the size of the data it has downloaded, and just returns it. -In this case you just have to assume that the download was successful]{2.5} - -\end{funcdesc} - -\begin{datadesc}{_urlopener} -The public functions \function{urlopen()} and -\function{urlretrieve()} create an instance of the -\class{FancyURLopener} class and use it to perform their requested -actions. To override this functionality, programmers can create a -subclass of \class{URLopener} or \class{FancyURLopener}, then assign -an instance of that class to the -\code{urllib._urlopener} variable before calling the desired function. -For example, applications may want to specify a different -\mailheader{User-Agent} header than \class{URLopener} defines. This -can be accomplished with the following code: - -\begin{verbatim} -import urllib - -class AppURLopener(urllib.FancyURLopener): - version = "App/1.7" - -urllib._urlopener = AppURLopener() -\end{verbatim} -\end{datadesc} - -\begin{funcdesc}{urlcleanup}{} -Clear the cache that may have been built up by previous calls to -\function{urlretrieve()}. -\end{funcdesc} - -\begin{funcdesc}{quote}{string\optional{, safe}} -Replace special characters in \var{string} using the \samp{\%xx} escape. -Letters, digits, and the characters \character{_.-} are never quoted. -The optional \var{safe} parameter specifies additional characters -that should not be quoted --- its default value is \code{'/'}. - -Example: \code{quote('/\~{}connolly/')} yields \code{'/\%7econnolly/'}. -\end{funcdesc} - -\begin{funcdesc}{quote_plus}{string\optional{, safe}} -Like \function{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 \var{safe}. It also -does not have \var{safe} default to \code{'/'}. -\end{funcdesc} - -\begin{funcdesc}{unquote}{string} -Replace \samp{\%xx} escapes by their single-character equivalent. - -Example: \code{unquote('/\%7Econnolly/')} yields \code{'/\~{}connolly/'}. -\end{funcdesc} - -\begin{funcdesc}{unquote_plus}{string} -Like \function{unquote()}, but also replaces plus signs by spaces, as -required for unquoting HTML form values. -\end{funcdesc} - -\begin{funcdesc}{urlencode}{query\optional{, doseq}} -Convert a mapping object or a sequence of two-element tuples to a -``url-encoded'' string, suitable to pass to -\function{urlopen()} above as the optional \var{data} argument. This -is useful to pass a dictionary of form fields to a \code{POST} -request. The resulting string is a series of -\code{\var{key}=\var{value}} pairs separated by \character{\&} -characters, where both \var{key} and \var{value} are quoted using -\function{quote_plus()} above. If the optional parameter \var{doseq} is -present and evaluates to true, individual \code{\var{key}=\var{value}} pairs -are generated for each element of the sequence. -When a sequence of two-element tuples is used as the \var{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 \refmodule{cgi} module provides the functions -\function{parse_qs()} and \function{parse_qsl()} which are used to -parse query strings into Python data structures. -\end{funcdesc} - -\begin{funcdesc}{pathname2url}{path} -Convert the pathname \var{path} from the local syntax for a path to -the form used in the path component of a URL. This does not produce a -complete URL. The return value will already be quoted using the -\function{quote()} function. -\end{funcdesc} - -\begin{funcdesc}{url2pathname}{path} -Convert the path component \var{path} from an encoded URL to the local -syntax for a path. This does not accept a complete URL. This -function uses \function{unquote()} to decode \var{path}. -\end{funcdesc} - -\begin{classdesc}{URLopener}{\optional{proxies\optional{, **x509}}} -Base class for opening and reading URLs. Unless you need to support -opening objects using schemes other than \file{http:}, \file{ftp:}, -\file{gopher:} or \file{file:}, you probably want to use -\class{FancyURLopener}. - -By default, the \class{URLopener} class sends a -\mailheader{User-Agent} header of \samp{urllib/\var{VVV}}, where -\var{VVV} is the \module{urllib} version number. Applications can -define their own \mailheader{User-Agent} header by subclassing -\class{URLopener} or \class{FancyURLopener} and setting the class -attribute \member{version} to an appropriate string value in the -subclass definition. - -The optional \var{proxies} parameter should be a dictionary mapping -scheme names to proxy URLs, where an empty dictionary turns proxies -off completely. Its default value is \code{None}, in which case -environmental proxy settings will be used if present, as discussed in -the definition of \function{urlopen()}, above. - -Additional keyword parameters, collected in \var{x509}, may be used for -authentication of the client when using the \file{https:} scheme. The keywords -\var{key_file} and \var{cert_file} are supported to provide an -SSL key and certificate; both are needed to support client authentication. - -\class{URLopener} objects will raise an \exception{IOError} exception -if the server returns an error code. -\end{classdesc} - -\begin{classdesc}{FancyURLopener}{...} -\class{FancyURLopener} subclasses \class{URLopener} providing default -handling for the following HTTP response codes: 301, 302, 303, 307 and -401. For the 30x response codes listed above, the -\mailheader{Location} header is used to fetch the actual URL. For 401 -response codes (authentication required), basic HTTP authentication is -performed. For the 30x response codes, recursion is bounded by the -value of the \var{maxtries} attribute, which defaults to 10. - -For all other response codes, the method \method{http_error_default()} -is called which you can override in subclasses to handle the error -appropriately. - -\note{According to the letter of \rfc{2616}, 301 and 302 responses to - POST requests must not be automatically redirected without - confirmation by the user. In reality, browsers do allow automatic - redirection of these responses, changing the POST to a GET, and - \module{urllib} reproduces this behaviour.} - -The parameters to the constructor are the same as those for -\class{URLopener}. - -\note{When performing basic authentication, a -\class{FancyURLopener} instance calls its -\method{prompt_user_passwd()} method. The default implementation asks -the users for the required information on the controlling terminal. A -subclass may override this method to support more appropriate behavior -if needed.} -\end{classdesc} - -\begin{excclassdesc}{ContentTooShortError}{msg\optional{, content}} -This exception is raised when the \function{urlretrieve()} function -detects that the amount of the downloaded data is less than the -expected amount (given by the \var{Content-Length} header). The -\member{content} attribute stores the downloaded (and supposedly -truncated) data. -\versionadded{2.5} -\end{excclassdesc} - -Restrictions: - -\begin{itemize} - -\item -Currently, only the following protocols are supported: HTTP, (versions -0.9 and 1.0), Gopher (but not Gopher-+), FTP, and local files. -\indexii{HTTP}{protocol} -\indexii{Gopher}{protocol} -\indexii{FTP}{protocol} - -\item -The caching feature of \function{urlretrieve()} has been disabled -until I find the time to hack proper processing of Expiration time -headers. - -\item -There should be a function to query whether a particular URL is in -the cache. - -\item -For backward compatibility, if a URL appears to point to a local file -but the file can't be opened, the URL is re-interpreted using the FTP -protocol. This can sometimes cause confusing error messages. - -\item -The \function{urlopen()} and \function{urlretrieve()} functions can -cause arbitrarily long delays while waiting for a network connection -to be set up. This means that it is difficult to build an interactive -Web client using these functions without using threads. - -\item -The data returned by \function{urlopen()} or \function{urlretrieve()} -is the raw data returned by the server. This may be binary data -(such as an image), plain text or (for example) HTML\index{HTML}. The -HTTP\indexii{HTTP}{protocol} protocol provides type information in the -reply header, which can be inspected by looking at the -\mailheader{Content-Type} header. For the -Gopher\indexii{Gopher}{protocol} protocol, type information is encoded -in the URL; there is currently no easy way to extract it. If the -returned data is HTML, you can use the module -\refmodule{htmllib}\refstmodindex{htmllib} to parse it. - -\item -The code handling the FTP\index{FTP} protocol cannot differentiate -between a file and a directory. This can lead to unexpected behavior -when attempting to read a URL that points to a file that is not -accessible. If the URL ends in a \code{/}, it is assumed to refer to -a directory and will be handled accordingly. But if an attempt to -read a file leads to a 550 error (meaning the URL cannot be found or -is not accessible, often for permission reasons), then the path is -treated as a directory in order to handle the case when a directory is -specified by a URL but the trailing \code{/} has been left off. This can -cause misleading results when you try to fetch a file whose read -permissions make it inaccessible; the FTP code will try to read it, -fail with a 550 error, and then perform a directory listing for the -unreadable file. If fine-grained control is needed, consider using the -\module{ftplib} module, subclassing \class{FancyURLOpener}, or changing -\var{_urlopener} to meet your needs. - -\item -This module does not support the use of proxies which require -authentication. This may be implemented in the future. - -\item -Although the \module{urllib} module contains (undocumented) routines -to parse and unparse URL strings, the recommended interface for URL -manipulation is in module \refmodule{urlparse}\refstmodindex{urlparse}. - -\end{itemize} - - -\subsection{URLopener Objects \label{urlopener-objs}} -\sectionauthor{Skip Montanaro}{skip@mojam.com} - -\class{URLopener} and \class{FancyURLopener} objects have the -following attributes. - -\begin{methoddesc}[URLopener]{open}{fullurl\optional{, data}} -Open \var{fullurl} using the appropriate protocol. This method sets -up cache and proxy information, then calls the appropriate open method with -its input arguments. If the scheme is not recognized, -\method{open_unknown()} is called. The \var{data} argument -has the same meaning as the \var{data} argument of \function{urlopen()}. -\end{methoddesc} - -\begin{methoddesc}[URLopener]{open_unknown}{fullurl\optional{, data}} -Overridable interface to open unknown URL types. -\end{methoddesc} - -\begin{methoddesc}[URLopener]{retrieve}{url\optional{, - filename\optional{, - reporthook\optional{, data}}}} -Retrieves the contents of \var{url} and places it in \var{filename}. The -return value is a tuple consisting of a local filename and either a -\class{mimetools.Message} object containing the response headers (for remote -URLs) or \code{None} (for local URLs). The caller must then open and read the -contents of \var{filename}. If \var{filename} is not given and the URL -refers to a local file, the input filename is returned. If the URL is -non-local and \var{filename} is not given, the filename is the output of -\function{tempfile.mktemp()} with a suffix that matches the suffix of the last -path component of the input URL. If \var{reporthook} is given, it must be -a function accepting three numeric parameters. It will be called after each -chunk of data is read from the network. \var{reporthook} is ignored for -local URLs. - -If the \var{url} uses the \file{http:} scheme identifier, the optional -\var{data} argument may be given to specify a \code{POST} request -(normally the request type is \code{GET}). The \var{data} argument -must in standard \mimetype{application/x-www-form-urlencoded} format; -see the \function{urlencode()} function below. -\end{methoddesc} - -\begin{memberdesc}[URLopener]{version} -Variable that specifies the user agent of the opener object. To get -\refmodule{urllib} to tell servers that it is a particular user agent, -set this in a subclass as a class variable or in the constructor -before calling the base constructor. -\end{memberdesc} - -The \class{FancyURLopener} class offers one additional method that -should be overloaded to provide the appropriate behavior: - -\begin{methoddesc}[FancyURLopener]{prompt_user_passwd}{host, realm} -Return information needed to authenticate the user at the given host -in the specified security realm. The return value should be a tuple, -\code{(\var{user}, \var{password})}, which can be used for basic -authentication. - -The implementation prompts for this information on the terminal; an -application should override this method to use an appropriate -interaction model in the local environment. -\end{methoddesc} - - -\subsection{Examples} -\nodename{Urllib Examples} - -Here is an example session that uses the \samp{GET} method to retrieve -a URL containing parameters: - -\begin{verbatim} ->>> import urllib ->>> params = urllib.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0}) ->>> f = urllib.urlopen("http://www.musi-cal.com/cgi-bin/query?%s" % params) ->>> print f.read() -\end{verbatim} - -The following example uses the \samp{POST} method instead: - -\begin{verbatim} ->>> import urllib ->>> params = urllib.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0}) ->>> f = urllib.urlopen("http://www.musi-cal.com/cgi-bin/query", params) ->>> print f.read() -\end{verbatim} - -The following example uses an explicitly specified HTTP proxy, -overriding environment settings: - -\begin{verbatim} ->>> import urllib ->>> proxies = {'http': 'http://proxy.example.com:8080/'} ->>> opener = urllib.FancyURLopener(proxies) ->>> f = opener.open("http://www.python.org") ->>> f.read() -\end{verbatim} - -The following example uses no proxies at all, overriding environment -settings: - -\begin{verbatim} ->>> import urllib ->>> opener = urllib.FancyURLopener({}) ->>> f = opener.open("http://www.python.org/") ->>> f.read() -\end{verbatim} |