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author | Guido van Rossum <guido@python.org> | 1994-01-02 01:22:07 (GMT) |
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committer | Guido van Rossum <guido@python.org> | 1994-01-02 01:22:07 (GMT) |
commit | 5fdeeeae2a12b9956cc84d62eae82f72cabc8664 (patch) | |
tree | ac0053479e10099850c8e0d06e31cb3afbf632bb /Doc/libmarshal.tex | |
parent | 0b0719866e8a32d0a787e73bca9e79df1d1a74f8 (diff) | |
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Restructured library documentation
Diffstat (limited to 'Doc/libmarshal.tex')
-rw-r--r-- | Doc/libmarshal.tex | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/Doc/libmarshal.tex b/Doc/libmarshal.tex new file mode 100644 index 0000000..2b0a400 --- /dev/null +++ b/Doc/libmarshal.tex @@ -0,0 +1,59 @@ +\section{Built-in Module \sectcode{marshal}} + +\bimodindex{marshal} +This module contains functions that can read and write Python +values in a binary format. The format is specific to Python, but +independent of machine architecture issues (e.g., you can write a +Python value to a file on a VAX, transport the file to a Mac, and read +it back there). Details of the format not explained here; read the +source if you're interested.% +\footnote{The name of this module stems from a bit of terminology used +by the designers of Modula-3 (amongst others), who use the term +``marshalling'' for shipping of data around in a self-contained form. +Strictly speaking, ``to marshal'' means to convert some data from +internal to external form (in an RPC buffer for instance) and +``unmarshalling'' for the reverse process.} + + +Not all Python object types are supported; in general, only objects +whose value is independent from a particular invocation of Python can +be written and read by this module. The following types are supported: +\code{None}, integers, long integers, floating point numbers, +strings, tuples, lists, dictionaries, and code objects, where it +should be understood that tuples, lists and dictionaries are only +supported as long as the values contained therein are themselves +supported; and recursive lists and dictionaries should not be written +(they will cause an infinite loop). + +There are functions that read/write files as well as functions +operating on strings. + +The module defines these functions: + +\renewcommand{\indexsubitem}{(in module marshal)} +\begin{funcdesc}{dump}{value\, file} + Write the value on the open file. The value must be a supported + type. The file must be an open file object such as + \code{sys.stdout} or returned by \code{open()} or + \code{posix.popen()}. + + If the value has an unsupported type, garbage is written which cannot + be read back by \code{load()}. +\end{funcdesc} + +\begin{funcdesc}{load}{file} + Read one value from the open file and return it. If no valid value + is read, raise \code{EOFError}, \code{ValueError} or + \code{TypeError}. The file must be an open file object. +\end{funcdesc} + +\begin{funcdesc}{dumps}{value} + Return the string that would be written to a file by + \code{dump(value, file)}. The value must be a supported type. +\end{funcdesc} + +\begin{funcdesc}{loads}{string} + Convert the string to a value. If no valid value is found, raise + \code{EOFError}, \code{ValueError} or \code{TypeError}. Extra + characters in the string are ignored. +\end{funcdesc} |