From 75cc891c56aced75497280f2d067767b908eed9b Mon Sep 17 00:00:00 2001
From: jyelon <jyelon@gmail.com>
Date: Tue, 14 Dec 2021 12:24:25 -0500
Subject: [PATCH] Restore ability to print return values.

---
 luprex/core/cpp/world-core.cpp | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/luprex/core/cpp/world-core.cpp b/luprex/core/cpp/world-core.cpp
index 317ccd85..420b5d2d 100644
--- a/luprex/core/cpp/world-core.cpp
+++ b/luprex/core/cpp/world-core.cpp
@@ -492,6 +492,7 @@ void World::invoke_lua(int64_t actor_id, int64_t place_id, const std::string &ac
     LS.rawset(thinfo, "actorid", actor_id);
     LS.rawset(thinfo, "nargs", 0);
     LS.rawset(thinfo, "useppool", true);
+    LS.rawset(thinfo, "print", true);
     
     // Store the thread into place's thread table.
     LS.rawget(threads, mt, "threads");
@@ -584,6 +585,7 @@ void World::invoke_plan(int64_t actor_id, int64_t place_id, const std::string &a
     LS.rawset(thinfo, "actorid", actor_id);
     LS.rawset(thinfo, "nargs", 3); // actor, place, invdata
     LS.rawset(thinfo, "useppool", true);
+    LS.rawset(thinfo, "print", false);
     
     // Store the thread into place's thread table.
     LS.rawget(threads, mt, "threads");
@@ -611,8 +613,8 @@ void World::invoke_tick(int64_t actor_id, int64_t place_id, const std::string &a
 void World::run_scheduled_threads() {
     assert(stack_is_clear());
     lua_State *L = state();
-    LuaVar tangibles, place, mt, threads, thinfo, actorid, nargs, useppool, thread;
-    LuaStack LS(L, tangibles, place, mt, threads, thinfo, actorid, nargs, useppool, thread);
+    LuaVar tangibles, place, mt, threads, thinfo, actorid, nargs, useppool, thread, print;
+    LuaStack LS(L, tangibles, place, mt, threads, thinfo, actorid, nargs, useppool, thread, print);
 
     LS.rawget(tangibles, LuaRegistry, "tangibles");
     while (thread_sched_.ready(clock_)) {
@@ -662,7 +664,6 @@ void World::run_scheduled_threads() {
         } else if (status == LUA_YIELD) {
             // If there's nothing on the stack, infer that tangible.nopredict yielded.
             if (lua_gettop(CO) == 0) {
-                // std::cerr << "Thread killed self using tangible.nopredict" << std::endl;
                 LS.rawset(threads, sched.thread_id(), LuaNil);
             }
             // If there's a single number on the stack, infer that 'wait' yielded.
@@ -671,9 +672,7 @@ void World::run_scheduled_threads() {
                 lua_settop(CO, 0);
                 LS.rawset(thinfo, "nargs", 0);
                 LS.rawset(thinfo, "useppool", false);
-                // std::cerr << "Thread wait = " << delay << std::endl;
                 thread_sched_.add(clock_ + int64_t(delay), sched.thread_id(), sched.place_id());
-                // std::cerr << "Added to schedule." << std::endl;
             }
             // In any other case, generate an error and kill the coroutine.
             else {
@@ -681,8 +680,15 @@ void World::run_scheduled_threads() {
                 LS.rawset(threads, sched.thread_id(), LuaNil);
             }
         } else if (status == LUA_OK) {
-            // Successfully ran to completion.  Remove from thread table.
-            // std::cerr << "Thread ran to completion." << std::endl;
+            // Successfully ran to completion.  Print any return values.
+            // Remove from thread table.
+            LS.rawget(print, thinfo, "print");
+            LuaStack LSCO(CO);
+            if (LS.ckboolean(print)) {
+                for (int i = 1; i <= lua_gettop(CO); i++) {
+                    pprint(LSCO, LuaSpecial(i), true, ostream);
+                }
+            }
             LS.rawset(threads, sched.thread_id(), LuaNil);
         } else {
             // Generated an error.  Add a traceback, print, and kill the coroutine.