ob-perl: implement results interpretation and improve wrapper

* lisp/ob-perl.el (org-babel-execute:perl): Pass `result-params´
  through to `org-babel-perl-evaluate´.
* lisp/ob-perl.el (org-babel-variable-assignments:perl): Add "my" to
  variable declaration so that it becomes compatible with "use
  strict;".
* lisp/ob-perl.el (org-babel-varariable-assignments:perl): Use new
  internal formatting function `org-babel-perl--var-to-perl´.
* lisp/ob-perl.el (org-babel-perl--var-to-perl): New internal function, uses Perl
  non-interpolating quoting on the string that defines the variable to
  suppress spurious interpretation of it as Perl syntax.
* lisp/ob-perl.el (org-babel-perl-wrapper-method): Use a block and
  declare all variables as "my", also use Perl quoting throughout.
  Redirect STDOUT to the temporary file so that simply "print" will
  put the results there.  Check the return value and output in table
  form if it is an ARRAY ref, otherwise print it without a final
  newline.
* lisp/ob-perl.el (org-babel-perl-preface): Content of this variable
  is prepended to body before invocation of perl.
* lisp/ob-perl.el (org-babel-perl-evaluate): Rename input parameter
  body to ibody and let-bind body to concatentation of
  org-babel-perl-preface and ibody.  Implement results interpretation
  so that tables are easier to produce.

Following suggestions by Daniel M. German in
http://thread.gmane.org/gmane.emacs.orgmode/66855.

lisp/ob-perl.el

@@ -48,7 +48,7 @@ This function is called by `org-babel-execute-src-block'."
 		     body params (org-babel-variable-assignments:perl params)))
 	 (session (org-babel-perl-initiate-session session)))
     (org-babel-reassemble-table
-     (org-babel-perl-evaluate session full-body result-type)
+     (org-babel-perl-evaluate session full-body result-type result-params)
      (org-babel-pick-name
       (cdr (assoc :colname-names params)) (cdr (assoc :colnames params)))
      (org-babel-pick-name
@@ -62,9 +62,7 @@ This function is called by `org-babel-execute-src-block'."
   "Return list of perl statements assigning the block's variables."
   (mapcar
    (lambda (pair)
-     (format "$%s=%s;"
-	     (car pair)
-	     (org-babel-perl-var-to-perl (cdr pair))))
+     (org-babel-perl--var-to-perl (cdr pair) (car pair)))
    (mapcar #'cdr (org-babel-get-header params :var))))
 
 ;; helper functions
@@ -72,13 +70,25 @@ This function is called by `org-babel-execute-src-block'."
 (defvar org-babel-perl-var-wrap "q(%s)"
   "Wrapper for variables inserted into Perl code.")
 
-(defun org-babel-perl-var-to-perl (var)
+(defvar org-babel-perl--lvl)
+(defun org-babel-perl--var-to-perl (var &optional varn)
   "Convert an elisp value to a perl variable.
 The elisp value, VAR, is converted to a string of perl source code
 specifying a var of the same value."
-  (if (listp var)
-      (concat "[" (mapconcat #'org-babel-perl-var-to-perl var ", ") "]")
-    (format org-babel-perl-var-wrap var)))
+  (if varn
+      (let ((org-babel-perl--lvl 0) (lvar (listp var)) prefix)
+	(concat "my $" (symbol-name varn) "=" (when lvar "\n")
+		(org-babel-perl--var-to-perl var)
+		";\n"))
+    (let ((prefix (make-string (* 2 org-babel-perl--lvl) ?\ )))
+      (concat prefix
+	      (if (listp var)
+		  (let ((org-babel-perl--lvl (1+ org-babel-perl--lvl)))
+		    (concat "[\n"
+			    (mapconcat #'org-babel-perl--var-to-perl var "")
+			    prefix "]"))
+		(concat "q(" (princ var) ")"))
+	      (unless (zerop org-babel-perl--lvl) ",\n")))))
 
 (defvar org-babel-perl-buffers '(:default . nil))
 
@@ -86,32 +96,53 @@ specifying a var of the same value."
   "Return nil because sessions are not supported by perl."
   nil)
 
-(defvar org-babel-perl-wrapper-method
-  "
-sub main {
-%s
-}
-@r = main;
-open(o, \">%s\");
-print o join(\"\\n\", @r), \"\\n\"")
+(defvar org-babel-perl-wrapper-method "{
+    my $babel_sub = sub {
+        %s
+    };
+    open my $BOH, qq(>%s) or die qq(Perl: Could not open output file.$/);
+    select $BOH;
+    my $rv = &$babel_sub();
+    my $rt = ref $rv;
+    if (qq(ARRAY) eq $rt) {
+        local $\\=$/;
+	foreach my $rv ( @$rv ) {
+	    my $rt = ref $rv;
+	    if (qq(ARRAY) eq $rt) {
+		print join q(|), @$rv;
+	    } else {
+		print $rv;
+	    }
+	}
+    } else {
+	print $rv;
+    }
+}")
+
+(defvar org-babel-perl-preface nil)
 
 (defvar org-babel-perl-pp-wrapper-method
   nil)
 
-(defun org-babel-perl-evaluate (session body &optional result-type)
+(defun org-babel-perl-evaluate (session ibody &optional result-type result-params)
   "Pass BODY to the Perl process in SESSION.
 If RESULT-TYPE equals 'output then return a list of the outputs
 of the statements in BODY, if RESULT-TYPE equals 'value then
 return the value of the last statement in BODY, as elisp."
   (when session (error "Sessions are not supported for Perl"))
-  (case result-type
-    (output (org-babel-eval org-babel-perl-command body))
-    (value (let ((tmp-file (org-babel-temp-file "perl-")))
-	     (org-babel-eval
-	      org-babel-perl-command
-	      (format org-babel-perl-wrapper-method body
-		      (org-babel-process-file-name tmp-file 'noquote)))
-	     (org-babel-eval-read-file tmp-file)))))
+  (let ((body (concat org-babel-perl-preface ibody)))
+    (case result-type
+      (output (org-babel-eval org-babel-perl-command body))
+      (value (let ((tmp-file (org-babel-temp-file "perl-")))
+	       (org-babel-eval
+		org-babel-perl-command
+		(format org-babel-perl-wrapper-method body
+			(org-babel-process-file-name tmp-file 'noquote)))
+	       	(org-babel-result-cond result-params
+		  (with-temp-buffer
+		    (insert-file-contents tmp-file)
+		    (buffer-string))
+		  (org-babel-import-elisp-from-file tmp-file '(16))))))))
 
 (provide 'ob-perl)