Let macros update their help string from the validate function

If the second return value from the validate function exists and is a
non-empty string, replace the macro's help text with that string.

Revert r6327, as this is a better solution to the same problem.

Closes #1413.

Originally committed to SVN as r6352.

aegisub/src/auto4_lua.cpp

@@ -596,16 +596,12 @@ namespace Automation4 {
 	LuaCommand::LuaCommand(lua_State *L)
 	: LuaFeature(L)
 	, display(check_wxstring(L, 1))
+	, help(get_wxstring(L, 2))
 	, cmd_type(cmd::COMMAND_NORMAL)
 	{
 		lua_getfield(L, LUA_REGISTRYINDEX, "filename");
 		cmd_name = STD_STR(wxString::Format("automation/lua/%s/%s", get_wxstring(L, -1), check_wxstring(L, 1)));
 
-		if (lua_isstring(L, 2))
-			help = get_wxstring(L, 2);
-		else if (lua_isfunction(L, 2))
-			cmd_type |= cmd::COMMAND_DYNAMIC_HELP;
-
 		if (!lua_isfunction(L, 3))
 			luaL_error(L, "The macro processing function must be a function");
 
@@ -618,11 +614,6 @@ namespace Automation4 {
 		// new table for containing the functions for this feature
 		lua_newtable(L);
 
-		// store help string function
-		lua_pushstring(L, "help");
-		lua_pushvalue(L, 2);
-		lua_rawset(L, -3);
-
 		// store processing function
 		lua_pushstring(L, "run");
 		lua_pushvalue(L, 3);
@@ -650,17 +641,6 @@ namespace Automation4 {
 		LuaScript::GetScriptObject(L)->UnregisterCommand(this);
 	}
 
-	wxString LuaCommand::StrHelp() const
-	{
-		if (!(cmd_type & cmd::COMMAND_DYNAMIC_HELP)) return help;
-
-		GetFeatureFunction("help");
-		lua_pcall(L, 0, 1, 0);
-		wxString result = get_wxstring(L, -1);
-		lua_pop(L, 1);
-		return result;
-	}
-
 	static int transform_selection(lua_State *L, const agi::Context *c)
 	{
 		std::set<AssDialogue*> sel = c->selectionController->GetSelectedSet();
@@ -695,18 +675,25 @@ namespace Automation4 {
 		LuaAssFile *subsobj = new LuaAssFile(L, c->ass);
 		lua_pushinteger(L, transform_selection(L, c));
 
-		int err = lua_pcall(L, 3, 1, 0);
+		int err = lua_pcall(L, 3, 2, 0);
 
 		subsobj->ProcessingComplete();
 
-		bool result = false;
+		if (err) {
-		if (err)
 			wxLogWarning("Runtime error in Lua macro validation function:\n%s", get_wxstring(L, -1));
-		else
-			result = !!lua_toboolean(L, -1);
-
-		// clean up stack (result or error message)
 			lua_pop(L, 1);
+			return false;
+		}
+
+		bool result = !!lua_toboolean(L, -2);
+
+		wxString new_help_string(get_wxstring(L, -1));
+		if (new_help_string.size()) {
+			help = new_help_string;
+			cmd_type |= cmd::COMMAND_DYNAMIC_HELP;
+		}
+
+		lua_pop(L, 2);
 
 		return result;
 	}

aegisub/src/auto4_lua.h

@@ -259,7 +259,7 @@ namespace Automation4 {
 		const char* name() const { return cmd_name.c_str(); }
 		wxString StrMenu(const agi::Context *) const { return display; }
 		wxString StrDisplay(const agi::Context *) const { return display; }
-		wxString StrHelp() const;
+		wxString StrHelp() const { return help; }
 
 		int Type() const { return cmd_type; }
 

aegisub/src/menu.cpp

@@ -146,12 +146,12 @@ class CommandManager {
 	void UpdateItem(std::pair<std::string, wxMenuItem*> const& item) {
 		cmd::Command *c = cmd::get(item.first);
 		int flags = c->Type();
+		if (flags & cmd::COMMAND_VALIDATE)
+			item.second->Enable(c->Validate(context));
 		if (flags & cmd::COMMAND_DYNAMIC_NAME)
 			UpdateItemName(item);
 		if (flags & cmd::COMMAND_DYNAMIC_HELP)
 			item.second->SetHelp(c->StrHelp());
-		if (flags & cmd::COMMAND_VALIDATE)
-			item.second->Enable(c->Validate(context));
 		if (flags & cmd::COMMAND_RADIO || flags & cmd::COMMAND_TOGGLE) {
 			bool check = c->IsActive(context);
 			// Don't call Check(false) on radio items as this causes wxGtk to