From 8c71db0234142c3b45352773ab98e68b0bc7ad11 Mon Sep 17 00:00:00 2001
From: Jose Antonio Ortega Ruiz <jao@gnu.org>
Date: Sat, 4 Sep 2010 21:17:12 +0200
Subject: REPL: (optionally) forget old errors on new expressions

---
 doc/geiser.texi      | 16 ++++------------
 doc/repl.texi        | 27 +++++++++++++++++++++------
 elisp/geiser-repl.el | 13 +++++++++++++
 3 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/doc/geiser.texi b/doc/geiser.texi
index afd71e9..61e99fb 100644
--- a/doc/geiser.texi
+++ b/doc/geiser.texi
@@ -46,6 +46,8 @@ The document was typeset with
 @node Top, Introduction, (dir), (dir)
 @top Geiser
 
+@include top.texi
+
 @menu
 * Introduction::
 * Installation::
@@ -81,7 +83,8 @@ The REPL
 * Starting the REPL::
 * First aids::
 * Switching context::
-* Let Geiser spy::
+* Completion and error handling::
+* Autodoc and friends::
 * Customization and tips::
 
 Fun between the parens
@@ -96,19 +99,8 @@ Fun between the parens
 @end detailmenu
 @end menu
 
-@include top.texi
-
 @insertcopying
 
-@menu
-* Introduction::
-* Installation::
-* The REPL::
-* Fun between the parens::
-* Index::
-
-@end menu
-
 @end ifnottex
 
 @include intro.texi
diff --git a/doc/repl.texi b/doc/repl.texi
index d8583df..b314172 100644
--- a/doc/repl.texi
+++ b/doc/repl.texi
@@ -9,7 +9,8 @@ ready, just come back here and proceed to the following sections.
 * Starting the REPL::
 * First aids::
 * Switching context::
-* Let Geiser spy::
+* Completion and error handling::
+* Autodoc and friends::
 * Customization and tips::
 @end menu
 
@@ -85,7 +86,7 @@ as explained @ref{switching-repl-buff,,here}).
 
 The remaining commands are meatier, and deserve sections of their own.
 
-@node Switching context, Let Geiser spy, First aids, The REPL
+@node Switching context, Completion and error handling, First aids, The REPL
 @section Switching context
 
 @cindex current module, in REPL
@@ -118,8 +119,8 @@ a prefix-aware list of available module names.
 
 Which brings me to the next group of @repl{} commands.
 
-@node Let Geiser spy, Customization and tips, Switching context, The REPL
-@section Let Geiser spy, write and jump for you
+@node Completion and error handling, Autodoc and friends, Switching context, The REPL
+@section Completion and error handling
 
 @cindex completion, module name
 We've already seen Geiser completion of module names in action at the
@@ -132,7 +133,19 @@ starting with the prefix at point. Needless to say, this is not a static
 list, and it will grow as you define or import new bindings in the
 namespace at hand.
 
-But, oftentimes, there's more you'll want to know about an identifier
+REPL buffers use Emacs' compilation mode to highlight errors reported by
+the Scheme interpreter, and you can use the @command{next-error} command
+(@kbd{M-g n}) to jump to their location. By default, every time you
+enter a new expression for evaluation old error messages are forgotten,
+so that @kbd{M-g n} will always jump to errors related to the last
+evaluation request, if any. If you prefer a not so forgetful REPL, set
+the customization variable @code{geiser-repl-forget-old-errors-p} to
+@code{nil}.
+
+@node Autodoc and friends, Customization and tips, Completion and error handling, The REPL
+@section Autodoc and friends
+
+Oftentimes, there's more you'll want to know about an identifier
 besides its name: what module does it belong to? is it a procedure and,
 if so, what arguments does it take? Geiser tries to help you answering
 those questions too.
@@ -187,7 +200,7 @@ sections (but just perusing it's associated key bindings, by any of the
 methods we've already used for the @repl{}, will give you enough
 information to use it effectively enough).
 
-@node Customization and tips,  , Let Geiser spy, The REPL
+@node Customization and tips,  , Autodoc and friends, The REPL
 @section Customization and tips
 
 @cindex REPL customization
@@ -227,6 +240,8 @@ full path to the requisite binary.
 
 @cindex scheme load path
 @cindex scheme init file
+@cindex GUILE_LOAD_PATH
+@cindex PLTCOLLECTS
 You can also specify a couple more initialisation parameters. For Guile,
 @code{geiser-guile-load-path} is a list of paths to add to its load path
 when it's started, while @code{geiser-guile-init-file} is the path to an
diff --git a/elisp/geiser-repl.el b/elisp/geiser-repl.el
index dd85808..b8bb86d 100644
--- a/elisp/geiser-repl.el
+++ b/elisp/geiser-repl.el
@@ -79,6 +79,16 @@ implementation name gets appended to it."
   :type 'boolean
   :group 'geiser-repl)
 
+(geiser-custom--defcustom geiser-repl-forget-old-errors-p t
+  "Whether to forget old errors upon entering a new expression.
+
+When on (the default), every time a new expression is entered in
+the REPL old error messages are flushed, and using [[next-error]]
+afterwards will jump only to error locations produced by the new
+expression, if any."
+  :type 'boolean
+  :group 'geiser-repl)
+
 
 ;;; Geiser REPL buffers and processes:
 
@@ -402,6 +412,9 @@ module command as a string")
          (pmark (and proc (process-mark proc)))
          (intxt (and pmark (buffer-substring pmark (point)))))
     (when intxt
+      (when (and geiser-repl-forget-old-errors-p
+                 (not (geiser-con--is-debugging)))
+        (compilation-forget-errors))
       (comint-send-input)
       (when (string-match "^\\s-*$" intxt)
         (comint-send-string proc
-- 
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