From a1547bb047dfe66cffa4811d05fb08d98c6d81c6 Mon Sep 17 00:00:00 2001
From: Daniel Silverstone <dsilvers@digital-scurf.org>
Date: Sat, 4 Aug 2012 11:37:01 +0100
Subject: SUPPLE: Refine error reporting a little more

---
 example/simple-example.lua | 48 ++++++++++++++++++++++++++++++++++++++++++----
 lib/supple/comms.lua       |  9 ++++++---
 2 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/example/simple-example.lua b/example/simple-example.lua
index 327167f..af19499 100644
--- a/example/simple-example.lua
+++ b/example/simple-example.lua
@@ -41,15 +41,55 @@ local mt = {
 
 setmetatable(tab, mt)
 
+local function lprint(...)
+   local foo = {n=select("#",...),...}
+   if foo[1] then
+      print "Function ran OK:"
+   else
+      print "Error encountered:"
+   end
+   for i = 2, foo.n do
+      print(foo[i])
+   end
+   print()
+end
+
 -- Finally, run the subcode
-print(supple.host.run(subcode, "@test-code", tab))
+lprint(supple.host.run(subcode, "@test-code", tab))
 assert(tab.tot == 24)
 
 -- Now run a supple command which we expect to error out.
-print(supple.host.run("unknown()", "@test-code"))
+lprint(supple.host.run("unknown()", "@test-code"))
 
 -- And now, one where we pass an error from host to sandbox and back
-print(supple.host.run("local f = ... f()", "@test-code", function() unknown() end))
+lprint(supple.host.run("local f = ... f()", "@test-code", function() unknown() end))
 
 -- And now, one where we pass an error from sandbox to host to sandbox and back
-print(supple.host.run("local f = ... f(function() unknown() end)", "@test-code", function(ff) ff() end))
+lprint(supple.host.run("local f = ... f(function() unknown() end)", "@test-code", function(ff) ff() end))
+
+-- And finally, a reasonable traceback via named functions on each end...
+
+local errsrc = [[
+      function raises()
+	 does_not_exist()
+      end
+      
+      function passes()
+	 raises()
+      end
+
+      function chains(f)
+	 f(passes)
+      end
+
+      local callme = ...
+
+      callme(chains)
+]]
+
+function loopback(f)
+   f(loopback)
+end
+
+lprint(supple.host.run(errsrc, "@error-code", loopback))
+
diff --git a/lib/supple/comms.lua b/lib/supple/comms.lua
index 25aeb39..d175bff 100644
--- a/lib/supple/comms.lua
+++ b/lib/supple/comms.lua
@@ -20,6 +20,7 @@ local tonumber = tonumber
 local error = error
 local getinfo = debug.getinfo
 local concat = table.concat
+local xpcall = xpcall
 
 local fd = -1
 
@@ -55,9 +56,11 @@ local function captcha(msg)
    local traceback = {}
    local level = 2
    local info = getinfo(level, "Snlf")
-   while info do
-      if info.currentline > 0 and 
-	 not info.short_src:match("/supple/[^%.]+%.lua$") then
+   local function in_supple()
+      return info.short_src:match("/supple/[^%.]+%.lua$")
+   end
+   while info and info.func ~= xpcall do
+      if info.currentline > 0 and not in_supple() then
 	 local ttype, tag = objects.find_tag(info.func)
 	 if ttype then
 	    info.name = tag
-- 
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