Enhanced pdbtrack to provide for source code that's not findable by

the reported path.  (Eg, precompiled scripts with a file path suitable
for a different host, scripts actually running on a remote system or
with no valid path, like Zope through-the-web python scripts.)

On failing to find the code on the reported path, pdbtrack takes the
function name and looks through the buffers, from most to least
recent, seeking the first python-mode buffer that either is named for
the function or has a definition (def or class) for that function.  So
to get source tracking for code that's not located where the path
indicates, you put a copy of the script in a buffer, and pdbtrack will
find it.

Also, fixed a small bug so pdbtrack now properly presents the overlay
arrow when you run the pdb 'w'here command.

Misc/python-mode.el

@@ -472,7 +472,8 @@ Currently-active file is at the head of the list.")
 
 ;; pdbtrack contants
 (defconst py-pdbtrack-stack-entry-regexp
-  "> \\([^(]+\\)(\\([0-9]+\\))[?a-zA-Z0-9_]+()"
+;  "^> \\([^(]+\\)(\\([0-9]+\\))\\([?a-zA-Z0-9_]+\\)()"
+  "^> \\(.*\\)(\\([0-9]+\\))\\([?a-zA-Z0-9_]+\\)()"
   "Regular expression pdbtrack uses to find a stack trace entry.")
 
 (defconst py-pdbtrack-input-prompt "\n[(<]?pdb[>)]? "
@@ -1276,49 +1277,124 @@ Activity is disabled if the buffer-local variable
 `py-pdbtrack-do-tracking-p' is nil.
 
 We depend on the pdb input prompt matching `py-pdbtrack-input-prompt'
-at the beginning of the line."
+at the beginning of the line.
+
+If the traceback target file path is invalid, we look for the most
+recently visited python-mode buffer which either has the name of the
+current function \(or class) or which defines the function \(or
+class).  This is to provide for remote scripts, eg, Zope's 'Script
+(Python)' - put a _copy_ of the script in a python-mode buffer named
+for the script and pdbtrack will find it.)"
   ;; Instead of trying to piece things together from partial text
   ;; (which can be almost useless depending on Emacs version), we
   ;; monitor to the point where we have the next pdb prompt, and then
   ;; check all text from comint-last-input-end to process-mark.
   ;;
-  ;; KLM: It might be nice to provide an optional override, so this
-  ;; routine could be fed debugger output strings as the text
-  ;; argument, for deliberate application elsewhere.
-  ;;
-  ;; KLM: We're very conservative about clearing the overlay arrow, to
-  ;; minimize residue.  This means, for instance, that executing other
-  ;; pdb commands wipes out the highlight.
+  ;; Also, we're very conservative about clearing the overlay arrow,
+  ;; to minimize residue.  This means, for instance, that executing
+  ;; other pdb commands wipe out the highlight.  You can always do a
+  ;; 'where' (aka 'w') command to reveal the overlay arrow.
   (let* ((origbuf (current-buffer))
 	 (currproc (get-buffer-process origbuf)))
+
     (if (not (and currproc py-pdbtrack-do-tracking-p))
         (py-pdbtrack-overlay-arrow nil)
-      (let* (;(origdir default-directory)
-             (procmark (process-mark currproc))
+
+      (let* ((procmark (process-mark currproc))
              (block (buffer-substring (max comint-last-input-end
                                            (- procmark
                                               py-pdbtrack-track-range))
                                       procmark))
-             fname lineno)
+             target target_fname target_lineno)
+
         (if (not (string-match (concat py-pdbtrack-input-prompt "$") block))
             (py-pdbtrack-overlay-arrow nil)
-          (if (not (string-match
-                    (concat ".*" py-pdbtrack-stack-entry-regexp ".*")
-                    block))
-              (py-pdbtrack-overlay-arrow nil)
-            (setq fname (match-string 1 block)
-                  lineno (match-string 2 block))
-            (if (file-exists-p fname)
-                (progn
-                  (find-file-other-window fname)
-                  (goto-line (string-to-int lineno))
-                  (message "pdbtrack: line %s, file %s" lineno fname)
-                  (py-pdbtrack-overlay-arrow t)
-                  (pop-to-buffer origbuf t) )
-              (if (= (elt fname 0) ?\<)
-                  (message "pdbtrack: (Non-file source: '%s')" fname)
-                (message "pdbtrack: File not found: %s" fname))
-              )))))))
+
+          (setq target (py-pdbtrack-get-source-buffer block))
+
+          (if (stringp target)
+              (message "pdbtrack: %s" target)
+
+            (setq target_lineno (car target))
+            (setq target_buffer (cadr target))
+            (setq target_fname (buffer-file-name target_buffer))
+            (switch-to-buffer-other-window target_buffer)
+            (goto-line target_lineno)
+            (message "pdbtrack: line %s, file %s" target_lineno target_fname)
+            (py-pdbtrack-overlay-arrow t)
+            (pop-to-buffer origbuf t)
+
+            )))))
+  )
+
+(defun py-pdbtrack-get-source-buffer (block)
+  "Return line number and buffer of code indicated by block's traceback text.
+
+We look first to visit the file indicated in the trace.
+
+Failing that, we look for the most recently visited python-mode buffer
+with the same name or having 
+having the named function.
+
+If we're unable find the source code we return a string describing the
+problem as best as we can determine."
+
+  (if (not (string-match py-pdbtrack-stack-entry-regexp block))
+
+      "Traceback cue not found"
+
+    (let* ((filename (match-string 1 block))
+           (lineno (string-to-int (match-string 2 block)))
+           (funcname (match-string 3 block))
+           funcbuffer)
+
+      (cond ((file-exists-p filename)
+             (list lineno (find-file-noselect filename)))
+
+            ((setq funcbuffer (py-pdbtrack-grub-for-buffer funcname lineno))
+             (if (string-match "/Script (Python)$" filename)
+                 ;; Add in number of lines for leading '##' comments:
+                 (setq lineno
+                       (+ lineno
+                          (save-excursion
+                            (set-buffer funcbuffer)
+                            (count-lines
+                             (point-min)
+                             (string-match "^\\([^#]\\|#[^#]\\|#$\\)"
+                                           (buffer-substring (point-min)
+                                                             (point-max)
+                                                             funcbuffer)))))))
+             (list lineno funcbuffer))
+
+            ((= (elt filename 0) ?\<)
+             (format "(Non-file source: '%s')" filename))
+
+            (t (format "Function/file not found: %s(), %s" funcname filename)))
+      )
+    )
+  )
+
+(defun py-pdbtrack-grub-for-buffer (funcname lineno)
+  "Find most recent buffer itself named or having function funcname.
+
+Must have a least int(lineno) lines in it."
+  (let ((buffers (buffer-list))
+        ;(buffers (list (get-buffer "workflow_do_action.py")))
+        curbuf
+        got)
+    (while (and buffers (not got))
+      (setq buf (car buffers)
+            buffers (cdr buffers))
+      (if (or (save-excursion (set-buffer buf)
+                              (string= major-mode "python-mode"))
+              (and (string-match funcname (buffer-name buf))
+                   (string-match (concat "^\\s-*\\(def\\|class\\)\\s-+"
+                                         funcname "\\s-*(")
+                                 (buffer-substring (point-min buf)
+                                                   (point-max buf)
+                                                   buf))))
+          (setq got buf)))
+    got))
 
 (defun py-postprocess-output-buffer (buf)
   "Highlight exceptions found in BUF.