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diff --git a/Doc/ref/ref8.tex b/Doc/ref/ref8.tex new file mode 100644 index 0000000..a678f9f --- /dev/null +++ b/Doc/ref/ref8.tex @@ -0,0 +1,105 @@ +\chapter{Top-level components} + +The Python interpreter can get its input from a number of sources: +from a script passed to it as standard input or as program argument, +typed in interactively, from a module source file, etc. This chapter +gives the syntax used in these cases. +\index{interpreter} + +\section{Complete Python programs} +\index{program} + +While a language specification need not prescribe how the language +interpreter is invoked, it is useful to have a notion of a complete +Python program. A complete Python program is executed in a minimally +initialized environment: all built-in and standard modules are +available, but none have been initialized, except for \verb@sys@ +(various system services), \verb@__builtin__@ (built-in functions, +exceptions and \verb@None@) and \verb@__main__@. The latter is used +to provide the local and global name space for execution of the +complete program. +\refbimodindex{sys} +\refbimodindex{__main__} +\refbimodindex{__builtin__} + +The syntax for a complete Python program is that for file input, +described in the next section. + +The interpreter may also be invoked in interactive mode; in this case, +it does not read and execute a complete program but reads and executes +one statement (possibly compound) at a time. The initial environment +is identical to that of a complete program; each statement is executed +in the name space of \verb@__main__@. +\index{interactive mode} +\refbimodindex{__main__} + +Under {\UNIX}, a complete program can be passed to the interpreter in +three forms: with the {\bf -c} {\it string} command line option, as a +file passed as the first command line argument, or as standard input. +If the file or standard input is a tty device, the interpreter enters +interactive mode; otherwise, it executes the file as a complete +program. +\index{UNIX} +\index{command line} +\index{standard input} + +\section{File input} + +All input read from non-interactive files has the same form: + +\begin{verbatim} +file_input: (NEWLINE | statement)* +\end{verbatim} + +This syntax is used in the following situations: + +\begin{itemize} + +\item when parsing a complete Python program (from a file or from a string); + +\item when parsing a module; + +\item when parsing a string passed to the \verb@exec@ statement; + +\end{itemize} + +\section{Interactive input} + +Input in interactive mode is parsed using the following grammar: + +\begin{verbatim} +interactive_input: [stmt_list] NEWLINE | compound_stmt NEWLINE +\end{verbatim} + +Note that a (top-level) compound statement must be followed by a blank +line in interactive mode; this is needed to help the parser detect the +end of the input. + +\section{Expression input} +\index{input} + +There are two forms of expression input. Both ignore leading +whitespace. + +The string argument to \verb@eval()@ must have the following form: +\bifuncindex{eval} + +\begin{verbatim} +eval_input: condition_list NEWLINE* +\end{verbatim} + +The input line read by \verb@input()@ must have the following form: +\bifuncindex{input} + +\begin{verbatim} +input_input: condition_list NEWLINE +\end{verbatim} + +Note: to read `raw' input line without interpretation, you can use the +built-in function \verb@raw_input()@ or the \verb@readline()@ method +of file objects. +\obindex{file} +\index{input!raw} +\index{raw input} +\bifuncindex{raw_index} +\ttindex{readline} |