The other day I was working on an example which used tempfile() to create
file for use by the graphics device. And while I love tempfile()---as it is
portable and clever and the files get cleaned by R and all that---I noticed
one missing feature I would like to see: beside a starting name pattern, and
an optional directory, an 'file extension' argument would be nice to have.
As e.g. in
tmppdf<- tempfile(fileext=".pdf")
tmppng<- tempfile(fileext=".png")
tmpjpeg<- tempfile(fileext=".jpeg")
Below is a short and simple patch which extends tempfile() to three arguments
with the new one (fileext) defaulting to "". If set, the extension is
appended to what we got from R_tmpnam(). I made this non-vectorised; this
could be changed. I left R_tmpnam() alone as its interface appears in a
header. I updated the manual page too.
I wrote this again current R-devel source from SVN, the patch reflects
that. The patch applies cleanly to R-alpha as well where 'make check' passes
(and I only tried this as make check had issues with R-devel but devel being
devel I am not sure that it was this patch).
Now, I understand that tempfile() is used in a large number of places so I
more or less expect to get stone silence or a resounding "don't even think
about it". This end can always be achieved with a local function; but maybe
somebody else see merit in having this at the source.
Thanks for listening, and for considering this.
Regards, Dirk
Index: src/library/base/R/temp.R
===================================================================
--- src/library/base/R/temp.R (revision 54862)
+++ src/library/base/R/temp.R (working copy)
@@ -14,7 +14,7 @@
# A copy of the GNU General Public License is available at
# http://www.r-project.org/Licenses/
-tempfile<- function(pattern = "file", tmpdir = tempdir())
- .Internal(tempfile(pattern, tmpdir))
+tempfile<- function(pattern = "file", tmpdir = tempdir(), fileext = "")
+ .Internal(tempfile(pattern, tmpdir, fileext))
tempdir<- function() .Internal(tempdir())
Index: src/library/base/man/tempfile.Rd
===================================================================
--- src/library/base/man/tempfile.Rd (revision 54862)
+++ src/library/base/man/tempfile.Rd (working copy)
@@ -12,13 +12,14 @@
names for temporary files.
}
\usage{
-tempfile(pattern = "file", tmpdir = tempdir())
+tempfile(pattern = "file", tmpdir = tempdir(), fileext = "")
tempdir()
}
\arguments{
\item{pattern}{a non-empty character vector giving the initial part
of the name.}
\item{tmpdir}{a non-empty character vector giving the directory name}
+ \item{fileext}{an optional character object giving a file extension}
}
\value{
For \code{tempfile} a character vector giving the names of possible
@@ -55,6 +56,11 @@
contains a space in any of the components, the path returned will use
the shortnames version of the path.
#endif
+
+ The optional argument \code{fileext} can be use to supply a file
+ extension. This can be useful if the temporary file is for example use
+ with a graphics device as the file type can be signalled via the
+ extension; an example would be \code{fileext=".png"}.
}
\references{
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
Index: src/main/names.c
===================================================================
--- src/main/names.c (revision 54862)
+++ src/main/names.c (working copy)
@@ -786,7 +786,7 @@
{"file.info", do_fileinfo, 0, 11, 1, {PP_FUNCALL,
PREC_FN, 0}},
{"file.access", do_fileaccess, 0, 11, 2, {PP_FUNCALL,
PREC_FN, 0}},
{"dir.create", do_dircreate, 0, 11, 4, {PP_FUNCALL,
PREC_FN, 0}},
-{"tempfile", do_tempfile, 0, 11, 2, {PP_FUNCALL, PREC_FN,
0}},
+{"tempfile", do_tempfile, 0, 11, 3, {PP_FUNCALL, PREC_FN,
0}},
{"tempdir", do_tempdir, 0, 11, 0, {PP_FUNCALL, PREC_FN,
0}},
{"R.home", do_Rhome, 0, 11, 0, {PP_FUNCALL, PREC_FN,
0}},
{"date", do_date, 0, 11, 0, {PP_FUNCALL, PREC_FN,
0}},
Index: src/main/sysutils.c
===================================================================
--- src/main/sysutils.c (revision 54862)
+++ src/main/sysutils.c (working copy)
@@ -233,30 +233,44 @@
SEXP attribute_hidden do_tempfile(SEXP call, SEXP op, SEXP args, SEXP env)
{
- SEXP ans, pattern, tempdir;
- const char *tn, *td;
+ SEXP ans, pattern, fileext, tempdir;
+ const char *tn, *td, *te;
char *tm;
- int i, n1, n2, slen;
+ int i, n1, n2, n3, slen;
+ char tmp1[PATH_MAX];
checkArity(op, args);
- pattern = CAR(args); n1 = length(pattern);
- tempdir = CADR(args); n2 = length(tempdir);
+ pattern = CAR(args); n1 = length(pattern); args = CDR(args);
+ tempdir = CAR(args); n2 = length(tempdir); args = CDR(args);
+ fileext = CAR(args); n3 = length(fileext);
if (!isString(pattern))
error(_("invalid filename pattern"));
if (!isString(tempdir))
error(_("invalid '%s' value"), "tempdir");
+ if (!isString(fileext))
+ error(_("invalid pattern for end-of-filename"));
if (n1< 1)
error(_("no 'pattern'"));
if (n2< 1)
error(_("no 'tempdir'"));
+ /* fileext is optional and defaults to "" so no test for vector*/
+ if (n3 != 1)
+ error(_("only single argument for end-of-filename pattern supported"));
slen = (n1> n2) ? n1 : n2;
PROTECT(ans = allocVector(STRSXP, slen));
for(i = 0; i< slen; i++) {
tn = translateChar( STRING_ELT( pattern , i%n1 ) );
td = translateChar( STRING_ELT( tempdir , i%n2 ) );
+ te = translateChar( STRING_ELT( fileext , 0 ) );
/* try to get a new file name */
tm = R_tmpnam(tn, td);
- SET_STRING_ELT(ans, i, mkChar(tm));
+ if (0 != strlen(te)) {
+ /* append optional extension, or null string */
+ snprintf(tmp1, PATH_MAX, "%s%s", tm, te);
+ SET_STRING_ELT(ans, i, mkChar(tmp1));
+ } else {
+ SET_STRING_ELT(ans, i, mkChar(tm));
+ }
if(tm) free(tm);
}
UNPROTECT(1);
