Merge in Ping's changes to the cgitb documentation, and add a version

annotation as well.
This closes SF patch #494582.

Doc/lib/libcgitb.tex

@@ -3,38 +3,60 @@
 
 \declaremodule{standard}{cgitb}
 \modulesynopsis{Configurable traceback handler for CGI scripts.}
-\moduleauthor{Ka Ping Yee}{ping@lfw.org}
+\moduleauthor{Ka-Ping Yee}{ping@lfw.org}
 \sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
 
+\versionadded{2.2}
+\index{CGI!exceptions}
 \index{CGI!tracebacks}
+\index{exception!in CGI scripts}
 \index{traceback!in CGI scripts}
 
 The \module{cgitb} module provides a special exception handler for CGI
-scripts.  Using this module, an exception raised and left uncaught in
-a CGI script can be presented as colorized HTML in the user's Web
-browser.  The options to the \function{enable()} function can be used
-to control whether the colorized traceback is presented and whether
-the traceback is logged to a file for later analysis.
+scripts.  After this module is activated using the \function{enable()}
+function, if an uncaught exception occurs, a detailed, formatted
+report will be sent to the Web browser.  The report includes a
+traceback showing excerpts of the source code for each level, as well
+as the values of the arguments and local variables to currently
+running functions, to help you debug the problem.  Optionally, you can
+save this information to a file instead of sending it to the browser.
+
+To enable this feature, simply add one line to the top of your CGI script:
+
+\begin{verbatim}
+import cgitb; cgitb.enable()
+\end{verbatim}
+
+The options to the \function{enable()} function control whether the
+report is displayed in the browser and whether the report is logged
+to a file for later analysis.
 
 
 \begin{funcdesc}{enable}{\optional{display\optional{, logdir\optional{,
                          context}}}}
   This function causes the \module{cgitb} module to take over the
-  interpreters default handling for exceptions that propogate out of
-  the top level of a script.  The causes \module{cgitb} to set the
+  interpreter's default handling for exceptions by setting the
   value of \code{\refmodule{sys}.excepthook}.
+  \withsubitem{(in module sys)}{\ttindex{excepthook()}}
 
-  The optional argument \var{display} defaults to true and can be set
-  to false to suppress sending the traceback to the browser.
-  \var{logdir}, if given, should be a directory to cause tracebacks to
-  be written to files there; by default tracebacks will not be written
-  to files.  \var{context} is the number of lines of context around
-  the offending line in a traceback display; this defaults to
-  \code{5}.
+  The optional argument \var{display} defaults to \code{1} and can be set
+  to \code{0} to suppress sending the traceback to the browser.
+  If the argument \var{logdir} is present, the traceback reports are
+  written to files.  The value of \var{logdir} should be a directory
+  where these files will be placed.
+  The optional argument \var{context} is the number of lines of
+  context to display around the current line of source code in the
+  traceback; this defaults to \code{5}.
 \end{funcdesc}
 
 \begin{funcdesc}{handler}{\optional{info}}
-  This function handles an exception using the default settings.  This
-  can be used when you've caught an exception and want to report it
-  using \module{cgitb}, but need to continue processing.
+  This function handles an exception using the default settings
+  (that is, show a report in the browser, but don't log to a file).
+  This can be used when you've caught an exception and want to
+  report it using \module{cgitb}.  The optional \var{info} argument
+  should be a 3-tuple containing an exception type, exception
+  value, and traceback object, exactly like the tuple returned by
+  \code{\refmodule{sys}.exc_info()}.  If the \var{info} argument
+  is not supplied, the current exception is obtained from
+  \code{\refmodule{sys}.exc_info()}.
 \end{funcdesc}