lisp/ob-R.el: Fix tangling with tables

* lisp/ob-R.el (org-babel-R-assign-elisp): Fix variable transfer of
tables by using text connections in R instead of files.  Variable
transfer of tables does not depend on files anymore, i.e. works also
when tangling.

lisp/ob-R.el

@@ -190,32 +190,44 @@ This function is called by `org-babel-execute-src-block'."
   (if (listp value)
       (let* ((lengths (mapcar 'length (org-remove-if-not 'sequencep value)))
 	     (max (if lengths (apply 'max lengths) 0))
-	     (min (if lengths (apply 'min lengths) 0))
-	     (transition-file (org-babel-temp-file "R-import-")))
+	     (min (if lengths (apply 'min lengths) 0)))
         ;; Ensure VALUE has an orgtbl structure (depth of at least 2).
         (unless (listp (car value)) (setq value (list value)))
-        (with-temp-file transition-file
-          (insert
-	   (orgtbl-to-tsv value '(:fmt org-babel-R-quote-tsv-field))
-	   "\n"))
-	(let ((file (org-babel-process-file-name transition-file 'noquote))
+	(let ((file (orgtbl-to-tsv value '(:fmt org-babel-R-quote-tsv-field)))
 	      (header (if (or (eq (nth 1 value) 'hline) colnames-p)
 			  "TRUE" "FALSE"))
 	      (row-names (if rownames-p "1" "NULL")))
 	  (if (= max min)
-	      (format "%s <- read.table(\"%s\",
-                      header=%s,
-                      row.names=%s,
-                      sep=\"\\t\",
-                      as.is=TRUE)" name file header row-names)
-	    (format "%s <- read.table(\"%s\",
-                   header=%s,
-                   row.names=%s,
-                   sep=\"\\t\",
-                   as.is=TRUE,
-                   fill=TRUE,
-                   col.names = paste(\"V\", seq_len(%d), sep =\"\"))"
-		    name file header row-names max))))
+	      (format "%s <- local({
+                        con <- textConnection(
+                          %S
+                        )
+                        res <- read.table(
+                          con,
+                          header    = %s,
+                          row.names = %s,
+                          sep       = \"\\t\",
+                          as.is     = TRUE
+                        )
+                        close(con)
+                        res
+                        })" name file header row-names)
+	    (format "%s <- local({
+                       con <- textConnection(
+                         %S
+                       )
+                       res <- read.table(
+                         con,
+                         header    = %s,
+                         row.names = %s,
+                         sep       = \"\\t\",
+                         as.is     = TRUE,
+                         fill      = TRUE,
+                         col.names = paste(\"V\", seq_len(%d), sep =\"\")
+                       )
+                       close(con)
+                       res
+                       })" name file header row-names max))))
     (format "%s <- %s" name (org-babel-R-quote-tsv-field value))))
 
 (defvar ess-ask-for-ess-directory) ; dynamically scoped