by default use arg workaround

Author: siffiejoe

README.md

@@ -81,19 +81,16 @@ commandline) using the `-c` flag.
 
     ./amalg.lua -o out.lua -s main.lua -c
 
-That's it. For further info consult the source. Have fun!
-
+To fix a compatibility issue with Lua 5.1's vararg handling,
+`amalg.lua` by default adds a local alias to the global `arg` table to
+every loaded module. If for some reason you don't want that, use the
+`-a` flag (but be aware that in Lua 5.1 with `LUA_COMPAT_VARARG`
+defined (the default) your modules can only access the global `arg`
+table as `_G.arg`).
 
-##                              Gotchas                             ##
+    ./amalg.lua -o out.lua -a -s main.lua -c
 
-1.  If you are using Lua 5.1 with the `LUA_COMPAT_VARARG` flag defined
-    (the default), and you do your command line parsing in a module,
-    `arg` will *not* refer to the global `arg` table, but to a local
-    compatibility table that holds the same contents as the `...` list
-    of the module function (i.e. the required module name). Possible
-    workarounds are to use `_G.arg` in your module, to use the debug
-    flag `-d` for `amalg.lua`, or to precompile the argument parsing
-    module and put the binary module in the amalgamation.
+That's it. For further info consult the source. Have fun!
 
 
 ##                              Contact                             ##
@@ -108,7 +105,7 @@ Comments and feedback are always welcome.
 `amalg` is *copyrighted free software* distributed under the MIT
 license (the same license as Lua 5.1). The full license text follows:
 
-    amalg (c) 2013 Philipp Janda
+    amalg (c) 2013-2014 Philipp Janda
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the

src/amalg.lua

@@ -15,7 +15,7 @@ end
 
 
 local function parse_cmdline( ... )
-  local modules, use_cache, dbg, script, oname = {}, false, false
+  local modules, afix, use_cache, dbg, script, oname = {}, true
 
   local function set_oname( v )
     if v then
@@ -57,6 +57,8 @@ local function parse_cmdline( ... )
       use_cache = true
     elseif a == "-d" then
       dbg = true
+    elseif a == "-a" then
+      afix = false
     else
       local prefix = a:sub( 1, 2 )
       if prefix == "-o" then
@@ -69,7 +71,7 @@ local function parse_cmdline( ... )
     end
     i = i + 1
   end
-  return oname, script, dbg, use_cache, modules
+  return oname, script, dbg, afix, use_cache, modules
 end
 
 
@@ -142,7 +144,7 @@ end
 
 
 local function amalgamate( ... )
-  local oname, script, dbg, use_cache, modules = parse_cmdline( ... )
+  local oname, script, dbg, afix, use_cache, modules = parse_cmdline( ... )
 
   if use_cache then
     local c = readcache()
@@ -174,7 +176,8 @@ local function amalgamate( ... )
     else
       out:write( "local _ENV = _ENV\n",
                  "package.preload[ ", ("%q"):format( m ),
-                 " ] = function( ... ) _ENV = _ENV\n",
+                 " ] = function( ... ) ",
+                 afix and "local arg = _G.arg\n" or "_ENV = _ENV\n",
                  bytes, "\nend\n\n" )
     end
   end

tests/HISTO

@@ -2,8 +2,8 @@
 set -e
 
 LUAV=5.1
-LUAV=5.2
-LUAV=5.3
+#LUAV=5.2
+#LUAV=5.3
 
 echo "Using Lua $LUAV ..."
 luac$LUAV -o module1.luac module1.lua
@@ -21,6 +21,10 @@ lua$LUAV -e 'package.path = "./?.luac;"..package.path' ../src/amalg.lua -o binou
 echo -n "amalgamate modules and script in binary form ... "
 lua$LUAV binout.lua
 
+lua$LUAV ../src/amalg.lua -o afixout.lua -a -s main.lua module1 module2
+echo -n "amalgamate modules and script with arg fix ... "
+lua$LUAV afixout.lua
+
 lua$LUAV ../src/amalg.lua -o debugout.lua -d -s main.lua module1 module2
 echo -n "amalgamate modules and script with debug info ... "
 lua$LUAV debugout.lua
@@ -33,5 +37,5 @@ lua$LUAV cacheout.lua
 
 exit 0
 
-rm -f module1.luac module2.luac modules.lua textout.lua binout.lua debugout.lua cacheout.lua amalg.cache
+rm -f module1.luac module2.luac modules.lua textout.lua binout.lua afixout.lua debugout.lua cacheout.lua amalg.cache