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authorcinap_lenrek <cinap_lenrek@localhost>2011-05-03 11:25:13 +0000
committercinap_lenrek <cinap_lenrek@localhost>2011-05-03 11:25:13 +0000
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+\section{\module{code} ---
+ Interpreter base classes}
+\declaremodule{standard}{code}
+
+\modulesynopsis{Base classes for interactive Python interpreters.}
+
+
+The \code{code} module provides facilities to implement
+read-eval-print loops in Python. Two classes and convenience
+functions are included which can be used to build applications which
+provide an interactive interpreter prompt.
+
+
+\begin{classdesc}{InteractiveInterpreter}{\optional{locals}}
+This class deals with parsing and interpreter state (the user's
+namespace); it does not deal with input buffering or prompting or
+input file naming (the filename is always passed in explicitly).
+The optional \var{locals} argument specifies the dictionary in
+which code will be executed; it defaults to a newly created
+dictionary with key \code{'__name__'} set to \code{'__console__'}
+and key \code{'__doc__'} set to \code{None}.
+\end{classdesc}
+
+\begin{classdesc}{InteractiveConsole}{\optional{locals\optional{, filename}}}
+Closely emulate the behavior of the interactive Python interpreter.
+This class builds on \class{InteractiveInterpreter} and adds
+prompting using the familiar \code{sys.ps1} and \code{sys.ps2}, and
+input buffering.
+\end{classdesc}
+
+
+\begin{funcdesc}{interact}{\optional{banner\optional{,
+ readfunc\optional{, local}}}}
+Convenience function to run a read-eval-print loop. This creates a
+new instance of \class{InteractiveConsole} and sets \var{readfunc}
+to be used as the \method{raw_input()} method, if provided. If
+\var{local} is provided, it is passed to the
+\class{InteractiveConsole} constructor for use as the default
+namespace for the interpreter loop. The \method{interact()} method
+of the instance is then run with \var{banner} passed as the banner
+to use, if provided. The console object is discarded after use.
+\end{funcdesc}
+
+\begin{funcdesc}{compile_command}{source\optional{,
+ filename\optional{, symbol}}}
+This function is useful for programs that want to emulate Python's
+interpreter main loop (a.k.a. the read-eval-print loop). The tricky
+part is to determine when the user has entered an incomplete command
+that can be completed by entering more text (as opposed to a
+complete command or a syntax error). This function
+\emph{almost} always makes the same decision as the real interpreter
+main loop.
+
+\var{source} is the source string; \var{filename} is the optional
+filename from which source was read, defaulting to \code{'<input>'};
+and \var{symbol} is the optional grammar start symbol, which should
+be either \code{'single'} (the default) or \code{'eval'}.
+
+Returns a code object (the same as \code{compile(\var{source},
+\var{filename}, \var{symbol})}) if the command is complete and
+valid; \code{None} if the command is incomplete; raises
+\exception{SyntaxError} if the command is complete and contains a
+syntax error, or raises \exception{OverflowError} or
+\exception{ValueError} if the command contains an invalid literal.
+\end{funcdesc}
+
+
+\subsection{Interactive Interpreter Objects
+ \label{interpreter-objects}}
+
+\begin{methoddesc}{runsource}{source\optional{, filename\optional{, symbol}}}
+Compile and run some source in the interpreter.
+Arguments are the same as for \function{compile_command()}; the
+default for \var{filename} is \code{'<input>'}, and for
+\var{symbol} is \code{'single'}. One several things can happen:
+
+\begin{itemize}
+\item
+The input is incorrect; \function{compile_command()} raised an
+exception (\exception{SyntaxError} or \exception{OverflowError}). A
+syntax traceback will be printed by calling the
+\method{showsyntaxerror()} method. \method{runsource()} returns
+\code{False}.
+
+\item
+The input is incomplete, and more input is required;
+\function{compile_command()} returned \code{None}.
+\method{runsource()} returns \code{True}.
+
+\item
+The input is complete; \function{compile_command()} returned a code
+object. The code is executed by calling the \method{runcode()} (which
+also handles run-time exceptions, except for \exception{SystemExit}).
+\method{runsource()} returns \code{False}.
+\end{itemize}
+
+The return value can be used to decide whether to use
+\code{sys.ps1} or \code{sys.ps2} to prompt the next line.
+\end{methoddesc}
+
+\begin{methoddesc}{runcode}{code}
+Execute a code object.
+When an exception occurs, \method{showtraceback()} is called to
+display a traceback. All exceptions are caught except
+\exception{SystemExit}, which is allowed to propagate.
+
+A note about \exception{KeyboardInterrupt}: this exception may occur
+elsewhere in this code, and may not always be caught. The caller
+should be prepared to deal with it.
+\end{methoddesc}
+
+\begin{methoddesc}{showsyntaxerror}{\optional{filename}}
+Display the syntax error that just occurred. This does not display
+a stack trace because there isn't one for syntax errors.
+If \var{filename} is given, it is stuffed into the exception instead
+of the default filename provided by Python's parser, because it
+always uses \code{'<string>'} when reading from a string.
+The output is written by the \method{write()} method.
+\end{methoddesc}
+
+\begin{methoddesc}{showtraceback}{}
+Display the exception that just occurred. We remove the first stack
+item because it is within the interpreter object implementation.
+The output is written by the \method{write()} method.
+\end{methoddesc}
+
+\begin{methoddesc}{write}{data}
+Write a string to the standard error stream (\code{sys.stderr}).
+Derived classes should override this to provide the appropriate output
+handling as needed.
+\end{methoddesc}
+
+
+\subsection{Interactive Console Objects
+ \label{console-objects}}
+
+The \class{InteractiveConsole} class is a subclass of
+\class{InteractiveInterpreter}, and so offers all the methods of the
+interpreter objects as well as the following additions.
+
+\begin{methoddesc}{interact}{\optional{banner}}
+Closely emulate the interactive Python console.
+The optional banner argument specify the banner to print before the
+first interaction; by default it prints a banner similar to the one
+printed by the standard Python interpreter, followed by the class
+name of the console object in parentheses (so as not to confuse this
+with the real interpreter -- since it's so close!).
+\end{methoddesc}
+
+\begin{methoddesc}{push}{line}
+Push a line of source text to the interpreter.
+The line should not have a trailing newline; it may have internal
+newlines. The line is appended to a buffer and the interpreter's
+\method{runsource()} method is called with the concatenated contents
+of the buffer as source. If this indicates that the command was
+executed or invalid, the buffer is reset; otherwise, the command is
+incomplete, and the buffer is left as it was after the line was
+appended. The return value is \code{True} if more input is required,
+\code{False} if the line was dealt with in some way (this is the same as
+\method{runsource()}).
+\end{methoddesc}
+
+\begin{methoddesc}{resetbuffer}{}
+Remove any unhandled source text from the input buffer.
+\end{methoddesc}
+
+\begin{methoddesc}{raw_input}{\optional{prompt}}
+Write a prompt and read a line. The returned line does not include
+the trailing newline. When the user enters the \EOF{} key sequence,
+\exception{EOFError} is raised. The base implementation uses the
+built-in function \function{raw_input()}; a subclass may replace this
+with a different implementation.
+\end{methoddesc}