Pre-load pdx.lua and enable live-coding support by default.

Following up on rev. 7447be5, pdx.lua is now pre-loaded in pd.lua, and
all objects have live-coding enabled automatically, by calling
pdx.reload() immediately before intiialize().

Thus all you need is a `[; pdluax reload(` message in your patch, and
Bob's your uncle. Or you can add an instance of the pd-remote.pd
abstraction, as described in the tutorial, if you also want to remotely
control script reloads through your editor.

You can still disable this globally by commenting out the following line
near the end of pd.lua:

    pdx = require 'pdx'

Or you can disable reloads on a per-object basis by calling
pdx.unreload() in the intiialize() method. But why would you want to?
pdx.lua is well-tested at this point, incurs minimal overhead, and is by
far the easiest live-coding solution for pd-lua. Also, even with pdx.lua
pre-loaded, you can still use any of the other live-coding approaches
described in the tutorial if you prefer.

To make it possible to load pdx.lua from pd.lua (and possibly other
extension modules in the future), the extra/pdlua directory is now
always on Lua's `package.path`. Hence it was possible to revert
pd._setrequirepath() to take only one argument. (The present code won't
modify package.cpath, however. But this is fine with pdx.lua which is a
pure Lua module. And we can still add to package.cpath if a future
extension requires mixed Lua+C.)

pd.lua

@@ -29,15 +29,15 @@ pd._loadpath = ""
 pd._currentpath = ""
 
 -- add a path to Lua's "require" search paths
-pd._setrequirepath = function(path, pdlua_path)
+pd._setrequirepath = function(path)
   pd._packagepath = package.path
   pd._packagecpath = package.cpath
   if (pd._iswindows) then
-    package.path = path .. "\\?;" .. path .. "\\?.lua;" .. pdlua_path .. "\\?;" .. pdlua_path .. "\\?.lua;" .. package.path
-    package.cpath = path .. "\\?.dll;" .. pdlua_path .. "\\?.dll;" .. package.cpath
+    package.path = path .. "\\?;" .. path .. "\\?.lua;" .. package.path
+    package.cpath = path .. "\\?.dll;" .. package.cpath
   else
-    package.path = path .. "/?;" .. path .. "/?.lua;" .. pdlua_path .. "/?;" .. pdlua_path .. "/?.lua;" .. package.path
-    package.cpath = path .. "/?.so;" .. pdlua_path .. "/?.so;" .. package.cpath
+    package.path = path .. "/?;" .. path .. "/?.lua;" .. package.path
+    package.cpath = path .. "/?.so;" .. package.cpath
   end
 end
 
@@ -344,6 +344,9 @@ function pd.Class:construct(sel, atoms)
   self.inlets = 0
   self.outlets = 0
   self._canvaspath = pd._canvaspath(self._object) .. "/"
+  if pdx then
+    pdx.reload(self)
+  end
   if self:initialize(sel, atoms) then
     pd._createinlets(self._object, self.inlets)
     pd._createoutlets(self._object, self.outlets)
@@ -353,6 +356,9 @@ function pd.Class:construct(sel, atoms)
     self:postinitialize()
     return self
   else
+    if pdx then
+      pdx.unreload(self)
+    end
     return nil
   end
 end
@@ -517,4 +523,9 @@ end
 DATA = 0
 SIGNAL = 1
 Colors = {background = 0, foreground = 1, outline = 2}
+
+-- pre-load pdx.lua (live coding support); if you don't want this, just
+-- comment out the line below
+pdx = require 'pdx'
+
 -- fin pd.lua

pdlua.c

@@ -175,7 +175,7 @@ void initialise_lua_state()
 // In plugdata we're linked statically and thus c_externdir is empty.
 // So we pass a data directory to the setup function instead and store it here.
 // ag: Renamed to pdlua_datadir since we also need this in vanilla when
-// setting up the Lua search path when loading a pd_lua file.
+// setting up Lua's package.path.
 char pdlua_datadir[MAXPDSTRING];
 #if PLUGDATA
     // Hook to inform plugdata which class names are lua objects
@@ -2037,6 +2037,29 @@ static int pdlua_error(lua_State *L)
     return 0;
 }
 
+static void pdlua_packagepath(lua_State *L, const char *path)
+{
+    PDLUA_DEBUG("pdlua_packagepath: stack top %d", lua_gettop(L));
+    lua_getglobal(L, "package");
+    lua_pushstring(L, "path");
+    lua_gettable(L, -2);
+    const char *packagepath = lua_tostring(L, -1);
+    char *buf = malloc(2*strlen(path)+20+strlen(packagepath));
+    if (!buf) return;
+#ifdef _WIN32
+    sprintf(buf, "%s\\?;%s\\?.lua;%s", path, path, packagepath);
+#else
+    sprintf(buf, "%s/?;%s/?.lua;%s", path, path, packagepath);
+#endif
+    lua_pop(L, 1);
+    lua_pushstring(L, "path");
+    lua_pushstring(L, buf);
+    lua_settable(L, -3);
+    free(buf);
+    lua_pop(L, 1);
+    PDLUA_DEBUG("pdlua_packagepath: end. stack top %d", lua_gettop(L));
+}
+
 static void pdlua_setrequirepath
 ( /* FIXME: documentation (is this of any use at all?) */
     lua_State   *L,
@@ -2048,8 +2071,7 @@ static void pdlua_setrequirepath
     lua_pushstring(L, "_setrequirepath");
     lua_gettable(L, -2);
     lua_pushstring(L, path);
-    lua_pushstring(L, pdlua_datadir);
-    if (lua_pcall(L, 2, 0, 0) != 0)
+    if (lua_pcall(L, 1, 0, 0) != 0)
     {
         pd_error(NULL, "lua: internal error in `pd._setrequirepath': %s", lua_tostring(L, -1));
         lua_pop(L, 1);
@@ -2579,6 +2601,12 @@ void pdlua_setup(void)
     if (fd >= 0)
     { /* pd.lua was opened */
         reader.fd = fd;
+        // We need to set up Lua's package.path here so that pdx.lua can be
+        // found (and possibly other pre-loaded extension modules in the
+        // future). Note that we can't just use pdlua_setrequirepath() here
+        // because it calls pd._setrequirepath in pd.lua which isn't loaded
+        // yet at this point.
+        pdlua_packagepath(__L(), pdlua_datadir);
 #if LUA_VERSION_NUM	< 502
         result = lua_load(__L(), pdlua_reader, &reader, "pd.lua");
 #else // 5.2 style

pdlua/tutorial/examples/luatab.pd_lua

@@ -1,15 +1,10 @@
 local luatab = pd.Class:new():register("luatab")
 
--- our own pdlua extension, needed for the reload functionality
-local pdx = require 'pdx'
-
 function luatab:initialize(sel, atoms)
    -- single inlet for the frequency, bang goes to the single outlet when we
    -- finished generating a new waveform
    self.inlets = 1
    self.outlets = 1
-   -- enable the reload callback
-   pdx.reload(self)
    -- the name of the array/table should be in the 1st creation argument
    if type(atoms[1]) == "string" then
       self.tabname = atoms[1]

pdlua/tutorial/examples/pdx.lua

@@ -3,10 +3,8 @@
 pdx.lua: useful extensions to pd.lua
 Copyright (C) 2020 Albert Gräf <[email protected]>
 
-To use this in your pd-lua scripts: local pdx = require 'pdx'
-
 Currently there's only the pdx.reload() function, which implements a kind of
-remote reload functionality based on dofile and receivers, as explained in the
+live coding functionality based on dofile and receivers, as explained in the
 pd-lua tutorial. More may be added in the future.
 
 This program is free software; you can redistribute it and/or
@@ -30,6 +28,13 @@ local pdx = {}
 Reload functionality. Call pdx.reload() on your object to enable, and
 pdx.unreload() to disable this functionality again.
 
+NOTE: As of pd-lua 0.12.8, this module is now pre-loaded, and pdx.reload()
+gets called automatically before running the initialize method of any object,
+so calling pdx.reload() explicitly is no longer needed. (Old code importing
+the module and doing the call will continue to work, though.) Instead, you
+will now have to call pdx.unreload() in your initialize method if you want to
+*disable* this feature for some reason.
+
 pdx.reload installs a "pdluax" receiver which reloads the object's script file
 when it receives the "reload" message without any arguments, or a "reload
 class" message with a matching class name.