Re: Adding to the end of the load path

[Andreas Rottmann <a.rottmann@gmx.at>]

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Ian Price <ianprice90@googlemail.com> writes:

> Hi guilers,
>
> On the #guile IRC channel, Mark Weaver has stressed to me that he thinks
> it would be a good idea for us to be able to add paths to the end of the
> load path, since it would allow us to, for example, prefer a built-in guile
> implementation over a guildhall provided one, when this exists. Right
> now, for the srfi[0] and guile-lib, I have handled this by not adding
> files to the package where they have been adopted by guile (e.g. statprof).
>
> Andreas Rottmann suggested something similar in February[1].
>
I've attached a patch implementing that suggestion, FWIW.

> I don't have any concrete proposals better than what Andreas has
> suggested, but I felt I should make this post to the list, lest Mark and
> I forget.
>

[...]

> 1. http://lists.gnu.org/archive/html/guile-devel/2012-02/msg00038.html


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From 1f72ddd3971a796a6f83a68ebedde7d7324c50b5 Mon Sep 17 00:00:00 2001
From: Andreas Rottmann <a.rottmann@gmx.at>
Date: Thu, 8 Nov 2012 01:59:56 +0100
Subject: [PATCH] More flexible %load-path and %load-compiled-path handling

---
 libguile/load.c |   25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/libguile/load.c b/libguile/load.c
index af2ca45..a05cf76 100644
--- a/libguile/load.c
+++ b/libguile/load.c
@@ -226,7 +226,9 @@ SCM_DEFINE (scm_parse_path, "parse-path", 1, 1, 0,
 	    "Parse @var{path}, which is expected to be a colon-separated\n"
 	    "string, into a list and return the resulting list with\n"
 	    "@var{tail} appended. If @var{path} is @code{#f}, @var{tail}\n"
-	    "is returned.")
+	    "is returned.  In case an empty string occurs as an element\n"
+            "of @var{path}, @var{tail} is inserted at that point instead of\n"
+            "being append at the end of the list.")
 #define FUNC_NAME s_scm_parse_path
 {
 #ifdef __MINGW32__
@@ -237,9 +239,24 @@ SCM_DEFINE (scm_parse_path, "parse-path", 1, 1, 0,
   
   if (SCM_UNBNDP (tail))
     tail = SCM_EOL;
-  return (scm_is_false (path)
-	  ? tail
-	  : scm_append_x (scm_list_2 (scm_string_split (path, sep), tail)));
+  if (scm_is_false (path))
+    return tail;
+  else
+    {
+      SCM elements = scm_string_split (path, sep);
+      SCM seen = SCM_EOL;
+      SCM rest = elements;
+
+      for (; scm_is_pair (rest); rest = SCM_CDR (rest))
+        {
+          if (scm_is_true (scm_string_null_p (SCM_CAR (rest))))
+            return scm_append_x (scm_list_2 (scm_reverse_x (seen, tail),
+                                             SCM_CDR (rest)));
+          seen = scm_cons (SCM_CAR (rest), seen);
+        }
+
+      return scm_append_x (scm_list_2 (elements, tail));
+    }
 }
 #undef FUNC_NAME
 
-- 
1.7.10.4


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Regards, Rotty
-- 
Andreas Rottmann -- <http://rotty.yi.org/>