From e266a0e0889382031ff16231336ba8907bfb5ed9 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Tue, 8 Jun 2010 22:18:38 +0100
Subject: [PATCH] Print Lua stack trace on error

---
 scripts/init.lua    |  2 +-
 scripts/trading.lua |  2 +-
 scripts/uidemo.lua  |  6 +++---
 src/LuaWrap.cpp     | 38 ++++++++++++++++++++++++++++++++++++--
 src/Main.cpp        |  4 ----
 5 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/scripts/init.lua b/scripts/init.lua
index 4fef375..ccfb8d0 100644
--- a/scripts/init.lua
+++ b/scripts/init.lua
@@ -4,7 +4,7 @@
 _hooks = {}
 
 function _default_hook()
-   debug("_default_hook")
+   print("_default_hook")
 end
 
 function hook(tag, callback)
diff --git a/scripts/trading.lua b/scripts/trading.lua
index 48c1d6a..590fcfe 100644
--- a/scripts/trading.lua
+++ b/scripts/trading.lua
@@ -1,2 +1,2 @@
-debug("Hello from Lua!")
+print("Hello from Lua!")
 
diff --git a/scripts/uidemo.lua b/scripts/uidemo.lua
index 61d60d0..5d8b770 100644
--- a/scripts/uidemo.lua
+++ b/scripts/uidemo.lua
@@ -1,11 +1,11 @@
-debug("Lua UI demo!")
+print("Lua UI demo!")
 
 function btn2Click(btn)
-   debug("yahyahyah :D")
+   print("yahyahyah :D")
 end
 
 function layoutLoaded(layout)
-   debug("layout loaded")
+   print("layout loaded")
    layout:get("/wnd/btn2"):connect(
       gui.Widget.SIG_CLICK,
       btn2Click)
diff --git a/src/LuaWrap.cpp b/src/LuaWrap.cpp
index 780bbee..d7e345f 100644
--- a/src/LuaWrap.cpp
+++ b/src/LuaWrap.cpp
@@ -44,8 +44,33 @@ static int lua_log(lua_State *L)
    return 0;
 }
 
+static int lua_traceback(lua_State *L)
+{  
+   if (!lua_isstring(L, 1))
+      return 1;
+   
+   lua_getfield(L, LUA_GLOBALSINDEX, "debug");
+   if (!lua_istable(L, -1)) {
+      error() << "debug not table";
+ 
+      lua_pop(L, 1);
+      return 1;
+   }
+   
+   lua_getfield(L, -1, "traceback");
+   if (!lua_isfunction(L, -1)) {
+      lua_pop(L, 2);
+      return 1;
+   }
+   
+   lua_pushvalue(L, 1);
+   lua_pushinteger(L, 2); 
+   lua_call(L, 2, 1); 
+   return 1;
+}
+
 static luaL_Reg luaFuncs[] = {
-   { "debug", lua_debug },
+   { "print", lua_debug },
    { "log", lua_log },
    { NULL, NULL }
 };
@@ -76,6 +101,7 @@ LuaWrap::LuaWrap()
    luaopen_base(L);
    luaopen_string(L);
    luaopen_table(L);
+   luaopen_debug(L);
    
    lua_pushvalue(L, LUA_GLOBALSINDEX);
    luaL_register(L, NULL, luaFuncs);
@@ -91,18 +117,26 @@ LuaWrap::~LuaWrap()
 
 void LuaWrap::pcall(int nargs, int nresults)
 {
-   int result = lua_pcall(L, nargs, nresults, 0);
+   // Insert traceback function underneath arguments
+   int base = lua_gettop(L) - nargs;
+   lua_pushcfunction(L, lua_traceback);
+   lua_insert(L, base);
+  
+   int result = lua_pcall(L, nargs, nresults, base);
    
    switch (result) {
    case LUA_ERRRUN:
    case LUA_ERRERR:
       error() << lua_tolstring(L, -1, NULL);
       lua_pop(L, 1);
+      lua_gc(L, LUA_GCCOLLECT, 0);
       break;
    case LUA_ERRMEM:
       error() << "Lua out of memory!";
       break;
    }
+   
+   lua_remove(L, base);  // Remove traceback function
 }
 
 void LuaWrap::eval(const string& code)
diff --git a/src/Main.cpp b/src/Main.cpp
index 022587c..59a8410 100644
--- a/src/Main.cpp
+++ b/src/Main.cpp
@@ -20,7 +20,6 @@
 #include "GameScreens.hpp"
 #include "IResource.hpp"
 #include "IConfig.hpp"
-#include "ILua.hpp"
 
 #include <stdexcept>
 #include <iostream>
@@ -104,9 +103,6 @@ int main(int argc, char** argv)
       IConfigPtr cfg = getConfig();
       
       ::window = makeSDLWindow();
-
-      ILuaPtr lua = getLua();
-      lua->eval("debug(\"yahyahyah\")");
       
       IScreenPtr screen;
       if (::action == "edit") {
-- 
2.39.2