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Minor markup revisions for consistency with the rest of the documentation.

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Fred Drake 2000-09-05 13:50:21 +00:00
parent 0d83f68fc9
commit 8ff4cd7512
1 changed files with 33 additions and 33 deletions
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66
Doc/lib/libmmap.tex
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@ -8,20 +8,21 @@ Memory-mapped file objects behave like both mutable strings and like
file objects. You can use mmap objects in most places where strings
are expected; for example, you can use the \module{re} module to
search through a memory-mapped file. Since they're mutable, you can
change a single character by doing \code{obj[ \var{index} ] = 'a'}, or
change a single character by doing \code{obj[\var{index}] = 'a'}, or
change a substring by assigning to a slice:
\code{obj[ \var{i1}:\var{i2} ] = '...'}. You can also read and write
\code{obj[\var{i1}:\var{i2}] = '...'}. You can also read and write
data starting at the current file position, and \method{seek()}
through the file to different positions.
A memory-mapped file is created by the following function, which is
different on Unix and on Windows.
\begin{funcdesc}{mmap}{fileno, length \optional{, tagname} }
(Windows version) Maps \var{length} bytes from the file specified by
the file handle \var{fileno}, and returns a mmap object. If you wish
to map an existing Python file object, use its \method{fileno()}
method to obtain the correct value for the \var{fileno} parameter.
\begin{funcdesc}{mmap}{fileno, length\optional{, tagname}}
\strong{(Windows version)} Maps \var{length} bytes from the file
specified by the file handle \var{fileno}, and returns a mmap object.
If you wish to map an existing Python file object, use its
\method{fileno()} method to obtain the correct value for the
\var{fileno} parameter.
\var{tagname}, if specified, is a string giving a tag name for the mapping.
Windows allows you to have many different mappings against the same
@ -32,23 +33,24 @@ tag parameter will assist in keeping your code portable between Unix
and Windows.
\end{funcdesc}
\begin{funcdesc}{mmap}{fileno, size \optional{, flags, prot}}
(Unix version) Maps \var{length} bytes from the file specified by the
file handle \var{fileno}, and returns a mmap object. If you wish to
map an existing Python file object, use its \method{fileno()} method
to obtain the correct value for the \var{fileno} parameter.
\begin{funcdesc}{mmap}{fileno, size\optional{, flags, prot}}
\strong{(Unix version)} Maps \var{length} bytes from the file
specified by the file handle \var{fileno}, and returns a mmap object.
If you wish to map an existing Python file object, use its
\method{fileno()} method to obtain the correct value for the
\var{fileno} parameter.
\var{flags} specifies the nature of the mapping.
\code{MAP_PRIVATE} creates a private copy-on-write mapping, so
\constant{MAP_PRIVATE} creates a private copy-on-write mapping, so
changes to the contents of the mmap object will be private to this
process, and \code{MAP_SHARED} creates a mapping that's shared
process, and \constant{MAP_SHARED} creates a mapping that's shared
with all other processes mapping the same areas of the file.
The default value is \code{MAP_SHARED}.
The default value is \constant{MAP_SHARED}.
\var{prot}, if specified, gives the desired memory protection; the two
most useful values are \code{PROT_READ} and \code{PROT_WRITE}, to
specify that the pages may be read or written.
\var{prot} defaults to \code{PROT_READ | PROT_WRITE}.
most useful values are \constant{PROT_READ} and \constant{PROT_WRITE},
to specify that the pages may be read or written.
\var{prot} defaults to \constant{PROT_READ | PROT_WRITE}.
\end{funcdesc}
Memory-mapped file objects support the following methods:
@ -59,13 +61,13 @@ Close the file. Subsequent calls to other methods of the object
will result in an exception being raised.
\end{methoddesc}
\begin{methoddesc}{find}{\var{string} \optional{, \var{start}}}
Returns the lowest index in the object where the substring \var{string} is
found. Returns \code{-1} on failure.
\var{start} is the index at which the search begins, and defaults to zero.
\begin{methoddesc}{find}{string\optional{, start}}
Returns the lowest index in the object where the substring
\var{string} is found. Returns \code{-1} on failure. \var{start} is
the index at which the search begins, and defaults to zero.
\end{methoddesc}
\begin{methoddesc}{flush}{\optional{\var{offset}, \var{size}}}
\begin{methoddesc}{flush}{\optional{offset, size}}
Flushes changes made to the in-memory copy of a file back to disk.
Without use of this call there is no guarantee that changes are
written back before the object is destroyed. If \var{offset} and
@ -98,12 +100,11 @@ the next newline.
\begin{methoddesc}{resize}{\var{newsize}}
\end{methoddesc}
\begin{methoddesc}{seek}{\var{pos} \optional{, \var{whence}}}
Set the file's current position.
\var{whence} argument is optional and defaults to \code{0}
(absolute file positioning); other values are \code{1} (seek
relative to the current position) and \code{2} (seek relative to the
file's end).
\begin{methoddesc}{seek}{pos\optional{, whence}}
Set the file's current position.
\var{whence} argument is optional and defaults to \code{0} (absolute
file positioning); other values are \code{1} (seek relative to the
current position) and \code{2} (seek relative to the file's end).
\end{methoddesc}
\begin{methoddesc}{size}{}
@ -122,8 +123,7 @@ bytes that were written.
\end{methoddesc}
\begin{methoddesc}{write_byte}{\var{byte}}
Write the single-character string \var{byte} into memory at the current position of
the file pointer; the file position is advanced by 1.
Write the single-character string \var{byte} into memory at the
current position of the file pointer; the file position is advanced by
\code{1}.
\end{methoddesc}