@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
-@c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
+@c Copyright (C) 1990-1995, 1998-1999, 2001-2011
@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../../info/files
@defun file-truename filename
The function @code{file-truename} returns the truename of the file
-@var{filename}. The argument must be an absolute file name.
+@var{filename}. If the argument is not an absolute file name,
+this function first expands it against @code{default-directory}.
This function does not expand environment variables. Only
@code{substitute-in-file-name} does that. @xref{Definition of
@item
The file's inode number. If possible, this is an integer. If the
-inode number is too large to be represented as an integer in Emacs
-Lisp, but still fits into a 32-bit integer, then the value has the
-form @code{(@var{high} . @var{low})}, where @var{low} holds the low 16
-bits. If the inode is wider than 32 bits, the value is of the form
-@code{(@var{high} @var{middle} . @var{low})}, where @code{high} holds
-the high 24 bits, @var{middle} the next 24 bits, and @var{low} the low
-16 bits.
+inode number @math{N} is too large to be represented as an integer in
+Emacs Lisp, then the value has the form @code{(@var{high}
+. @var{low})}, where @var{high} holds the high bits (i.e., all but the
+low 16 bits) and @var{low} the low 16 bits.
@item
The filesystem number of the device that the file is on. Depending on
not an extension.
@end defun
-@ignore
-Andrew Innes says that this
-
-@c @defvar directory-sep-char
-This variable holds the character that Emacs normally uses to separate
-file name components. The default value is @code{?/}, but on MS-Windows
-you can set it to @code{?\\}; then the functions that transform file names
-use backslashes in their output.
-
-File names using backslashes work as input to Lisp primitives even on
-MS-DOS and MS-Windows, even if @code{directory-sep-char} has its default
-value of @code{?/}.
-@end defvar
-@end ignore
@node Relative File Names
@subsection Absolute and Relative File Names
is a good way to come up with one.
@end defun
+@defopt remote-file-name-inhibit-cache
+Whether to use the remote file-name cache for read access.
+
+File attributes of remote files are cached for better performance. If
+they are changed out of Emacs' control, the cached values become
+invalid, and must be reread.
+
+When set to @code{nil}, cached values are always used. This shall be
+set with care. When set to @code{t}, cached values are never used.
+ALthough this is the safest value, it could result in performance
+degradation.
+
+A compromise is to set it to a positive number. This means that
+cached values are used for that amount of seconds since they were
+cached.
+
+In case a remote file is checked regularly, it might be reasonable to
+let-bind this variable to a value less then the time period between
+two checks. Example:
+
+@example
+(defun display-time-file-nonempty-p (file)
+ (let ((remote-file-name-inhibit-cache (- display-time-interval 5)))
+ (and (file-exists-p file)
+ (< 0 (nth 7 (file-attributes (file-chase-links file)))))))
+@end example
+@end defopt
+
@node Format Conversion
@section File Format Conversion
names or values---because a program that general is probably difficult
to write, and slow. Instead, choose a set of possible data types that
are reasonably flexible, and not too hard to encode.
-
-@ignore
- arch-tag: 141f74ce-6ae3-40dc-a6c4-ef83fc4ec35c
-@end ignore
HCoop / bpt / emacs.git / blobdiff