From fefcd4ec405d444374cce2105b62e20344aa1240 Mon Sep 17 00:00:00 2001 From: Georg Brandl Date: Sun, 2 Dec 2007 14:34:34 +0000 Subject: Add example to mmap docs. Written for GHOP by Rafal Rawicki. --- Doc/library/mmap.rst | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/Doc/library/mmap.rst b/Doc/library/mmap.rst index 0e982c1..070ce4f 100644 --- a/Doc/library/mmap.rst +++ b/Doc/library/mmap.rst @@ -86,6 +86,49 @@ not update the underlying file. *offset* may be specified as a non-negative integer offset. mmap references will be relative to the offset from the beginning of the file. *offset* defaults to 0. *offset* must be a multiple of the PAGESIZE or ALLOCATIONGRANULARITY. + + This example shows a simple way of using :func:`mmap`:: + + import mmap + + # write a simple example file + with open("hello.txt", "w") as f: + f.write("Hello Python!\n") + + with open("hello.txt", "r+") as f: + # memory-map the file, size 0 means whole file + map = mmap.mmap(f.fileno(), 0) + # read content via standard file methods + print map.readline() # prints "Hello Python!" + # read content via slice notation + print map[:5] # prints "Hello" + # update content using slice notation; + # note that new content must have same size + map[6:] = " world!\n" + # ... and read again using standard file methods + map.seek(0) + print map.readline() # prints "Hello world!" + # close the map + map.close() + + + The next example demonstrates how to create an anonymous map and exchange + data between the parent and child processes:: + + import mmap + import os + + map = mmap.mmap(-1, 13) + map.write("Hello world!") + + pid = os.fork() + + if pid == 0: # In a child process + map.seek(0) + print map.readline() + + map.close() + Memory-mapped file objects support the following methods: -- cgit v0.12