give active mods a chance to reattach their hooks

docs/changelog.txt

@@ -46,6 +46,7 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 - `buildingplan`: items in the item selection dialog should now use the same item quality symbols as the base game
 - Mods: scripts in mods that are only in the steam workshop directory are now accessible. this means that a script-only mod that you never mark as "active" when generating a world will still receive automatic updates and be usable from in-game
 - Mods: scripts from only the most recent version of an installed mod are added to the script path
+- Mods: give active mods a chance to reattach their load hooks when a world is reloaded
 - `gui/control-panel`: bugfix services are now enabled by default
 
 ## Documentation

docs/guides/modding-guide.rst

@@ -461,6 +461,11 @@ Ok, you're all set up! Now, let's take a look at an example
     dfhack.onStateChange[GLOBAL_KEY] = function(sc)
         if sc == SC_MAP_UNLOADED then
             dfhack.run_command('disable', 'example-mod')
+
+            -- ensure our mod doesn't try to enable itself when a different
+            -- world is loaded where we are *not* active
+            dfhack.onStateChange[GLOBAL_KEY] = nil
+
             return
         end
 

library/Core.cpp

@@ -2148,7 +2148,10 @@ void Core::onStateChange(color_ostream &out, state_change_event event)
         loadModScriptPaths(out);
         auto L = Lua::Core::State;
         Lua::StackUnwinder top(L);
-        Lua::CallLuaModuleFunction(con, L, "script-manager", "reload");
+        Lua::CallLuaModuleFunction(con, L, "script-manager", "reload", 1, 0,
+            [](lua_State* L) {
+                Lua::Push(L, true);
+            });
         // fallthrough
     }
     case SC_WORLD_UNLOADED:

library/LuaApi.cpp

@@ -2729,7 +2729,7 @@ static int filesystem_listdir_recursive(lua_State *L)
         include_prefix = lua_toboolean(L, 3);
     std::map<std::string, bool> files;
     int err = DFHack::Filesystem::listdir_recursive(dir, files, depth, include_prefix);
-    if (err != -1) {
+    if (err != 0 && err != -1) {
         lua_pushnil(L);
         lua_pushstring(L, strerror(err));
         lua_pushinteger(L, err);

library/lua/script-manager.lua

@@ -6,22 +6,27 @@ local utils = require('utils')
 -- enabled API
 
 -- for each script that can be loaded as a module, calls cb(script_name, env)
-function foreach_module_script(cb)
+function foreach_module_script(cb, preprocess_script_file_fn)
     for _,script_path in ipairs(dfhack.internal.getScriptPaths()) do
         local files = dfhack.filesystem.listdir_recursive(
                                             script_path, nil, false)
         if not files then goto skip_path end
         for _,f in ipairs(files) do
-            if not f.isdir and
-                    f.path:endswith('.lua') and
-                    not f.path:startswith('test/') and
-                    not f.path:startswith('internal/') then
-                local script_name = f.path:sub(1, #f.path - 4) -- remove '.lua'
-                local ok, script_env = pcall(reqscript, script_name)
-                if ok then
-                    cb(script_name, script_env)
-                end
+            if f.isdir or not f.path:endswith('.lua') or
+                    f.path:startswith('.git') or
+                    f.path:startswith('test/') or
+                    f.path:startswith('internal/') then
+                goto continue
             end
+            if preprocess_script_file_fn then
+                preprocess_script_file_fn(script_path, f.path)
+            end
+            local script_name = f.path:sub(1, #f.path - 4) -- remove '.lua'
+            local ok, script_env = pcall(reqscript, script_name)
+            if ok then
+                cb(script_name, script_env)
+            end
+            ::continue::
         end
         ::skip_path::
     end
@@ -42,9 +47,17 @@ local function process_script(env_name, env)
     enabled_map[env_name] = fn
 end
 
-function reload()
+function reload(refresh_active_mod_scripts)
     enabled_map = utils.OrderedTable()
-    foreach_module_script(process_script)
+    local force_refresh_fn = refresh_active_mod_scripts and function(script_path, script_name)
+        if script_path:find('scripts_modactive') then
+            internal_script = dfhack.internal.scripts[script_path..'/'..script_name]
+            if internal_script then
+                internal_script.env = nil
+            end
+        end
+    end or nil
+    foreach_module_script(process_script, force_refresh_fn)
 end
 
 local function ensure_loaded()
@@ -97,7 +110,7 @@ end
 
 local function add_script_path(mod_script_paths, path)
     if dfhack.filesystem.isdir(path) then
-        print('indexing scripts from mod script path: ' .. path)
+        print('indexing mod scripts: ' .. path)
         table.insert(mod_script_paths, path)
     end
 end
@@ -120,7 +133,7 @@ function get_mod_script_paths()
     -- if a world is loaded, process active mods first, and lock to active version
     if dfhack.isWorldLoaded() then
         for _,path in ipairs(df.global.world.object_loader.object_load_order_src_dir) do
-            path = tostring(path)
+            path = tostring(path.value)
             if not path:startswith(INSTALLED_MODS_PATH) then goto continue end
             local id = get_mod_id_and_version(path)
             if not id then goto continue end