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Some programs need to write temporary files. Here is the usual way to construct a name for such a file:
(make-temp-file name-of-application) |
The job of make-temp-file is to prevent two different users or two
different jobs from trying to use the exact same file name.
This function creates a temporary file and returns its name. Emacs creates
the temporary file's name by adding to prefix some random characters
that are different in each Emacs job. The result is guaranteed to be a
newly created empty file. On MS-DOS, this function can truncate the
string prefix to fit into the 8+3 file-name limits. If prefix
is a relative file name, it is expanded against
temporary-file-directory.
(make-temp-file "foo")
⇒ "/tmp/foo232J6v"
|
When make-temp-file returns, the file has been created and is empty.
At that point, you should write the intended contents into the file.
If dir-flag is non-nil, make-temp-file creates an empty
directory instead of an empty file. It returns the file name, not the
directory name, of that directory. Voir la section Directory Names.
If suffix is non-nil, make-temp-file adds it at the end
of the file name.
To prevent conflicts among different libraries running in the same Emacs,
each Lisp program that uses make-temp-file should have its own
prefix. The number added to the end of prefix distinguishes
between the same application running in different Emacs jobs. Additional
added characters permit a large number of distinct names even in one Emacs
job.
The default directory for temporary files is controlled by the variable
temporary-file-directory. This variable gives the user a uniform way
to specify the directory for all temporary files. Some programs use
small-temporary-file-directory instead, if that is non-nil.
To use it, you should expand the prefix against the proper directory before
calling make-temp-file.
In older Emacs versions where make-temp-file does not exist, you
should use make-temp-name instead:
(make-temp-name
(expand-file-name name-of-application
temporary-file-directory))
|
This function generates a string that can be used as a unique file name.
The name starts with string, and has several random characters
appended to it, which are different in each Emacs job. It is like
make-temp-file except that it just constructs a name, and does not
create a file. Another difference is that string should be an
absolute file name. On MS-DOS, this function can truncate the string
prefix to fit into the 8+3 file-name limits.
This variable specifies the directory name for creating temporary files.
Its value should be a directory name (voir la section Directory Names), but it is
good for Lisp programs to cope if the value is a directory's file name
instead. Using the value as the second argument to expand-file-name
is a good way to achieve that.
The default value is determined in a reasonable way for your operating
system; it is based on the TMPDIR, TMP and TEMP
environment variables, with a fall-back to a system-dependent name if none
of these variables is defined.
Even if you do not use make-temp-file to create the temporary file,
you should still use this variable to decide which directory to put the file
in. However, if you expect the file to be small, you should use
small-temporary-file-directory first if that is non-nil.
This variable specifies the directory name for creating certain temporary files, which are likely to be small.
If you want to write a temporary file which is likely to be small, you should compute the directory like this:
(make-temp-file
(expand-file-name prefix
(or small-temporary-file-directory
temporary-file-directory)))
|
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Ce document a été généré par Eric Reinbold le 13 Octobre 2007 en utilisant texi2html 1.78.