Update python_easy_chess_gui.py

* Fix RuntimeError "main thread is not in main loop" that may appear from time to time when user selects computer opponent often. Use subprocess.popen to start the engine and get its id name.
* Remove parameter bind_return_key on list box.

Author: fsmosca

python_easy_chess_gui.py

@@ -58,7 +58,7 @@
 
 
 APP_NAME = 'Python Easy Chess GUI'
-APP_VERSION = 'v0.81'
+APP_VERSION = 'v0.82'
 BOX_TITLE = '{} {}'.format(APP_NAME, APP_VERSION)
 
 
@@ -1020,7 +1020,7 @@ def play_game(self, engine_id_name, board):
 
                                 try:
                                     self.engine_file = v['engine_file_k'][0]
-                                    engine_id_name = self.get_engine_id_name()
+                                    self.get_engine_id_name()
                                     self.update_engine_list()
                                 except:
                                     pass
@@ -1154,7 +1154,7 @@ def play_game(self, engine_id_name, board):
                         layout = [
                                 [sg.T('Current Opponent: {}'.format(self.opp_eng_id_name), size=(40,1))],
                                 [sg.Listbox(values=self.engine_list, size=(48,6),
-                                            bind_return_key = True, key='engine_file_k')],
+                                            key='engine_file_k')],
                                 [sg.T('Threads', size=(12, 1)), 
                                  sg.Spin([t for t in range(1, 9)], initial_value=self.threads,
                                           size=(8, 1), key='threads_k')],
@@ -1190,7 +1190,7 @@ def play_game(self, engine_id_name, board):
 
                                 try:
                                     self.engine_file = v['engine_file_k'][0]
-                                    engine_id_name = self.get_engine_id_name()
+                                    self.get_engine_id_name()
                                     self.update_engine_list()
                                 except:
                                     pass
@@ -1690,24 +1690,33 @@ def save_game(self):
             f.write('{}\n\n'.format(self.game)) 
 
     def get_engine_id_name(self):
-        """ Set the engine path and return id name """
+        """ Set the engine path """        
         cur_dir = Path.cwd()
         eng_path = Path(cur_dir, 'Engines', self.engine_file)
-        self.engine_path_and_name = eng_path
-        logging.info('engine path: {}'.format(eng_path))   
+        self.engine_path_and_name = eng_path                        
 
-        # Exit app if we fail to load the engine
-        if not eng_path.is_file():
-            logging.info('Quit app, failed to load engine.')
-            sys.exit(0)
-            
-        # Start the engine and get its id name for update to GUI
-        engine = chess.engine.SimpleEngine.popen_uci(str(self.engine_path_and_name))
-        self.opp_eng_id_name = engine.id['name']
-        engine.quit()
+        p = subprocess.Popen(str(eng_path), bufsize=1,
+                stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+                stderr=subprocess.STDOUT, universal_newlines=True,
+                creationflags=subprocess.CREATE_NO_WINDOW)
 
-        return self.opp_eng_id_name
-    
+        p.stdin.write('uci\n')
+        for eline in iter(p.stdout.readline, ''):
+            line = eline.strip()
+            if 'id name' in line:
+                engine_id_name = ' '.join(line.split()[2:]).strip()
+            if 'uciok' in line:
+                break
+
+        p.stdin.write('quit')
+        try:
+            p.communicate(timeout=5)
+        except subprocess.TimeoutExpired:
+            p.kill()
+            p.communicate()
+            
+        self.opp_eng_id_name = engine_id_name
+
     def get_engines(self):
         """ Returns a list of engines located in Engines dir """
         engine_list = []
@@ -1870,7 +1879,8 @@ def main_loop(self):
 
         # Define the opponent engine to use, this is the first engine in the list
         self.engine_file = self.engine_list[0]        
-        engine_id_name = self.get_engine_id_name()
+        self.get_engine_id_name()
+        engine_id_name = self.opp_eng_id_name
 
         self.adviser_engine = self.engine_list[0]
         self.adviser_engine_path = Path('Engines', self.adviser_engine)
@@ -1913,7 +1923,7 @@ def main_loop(self):
                 layout = [
                         [sg.T('Current Opponent: {}'.format(self.opp_eng_id_name), size=(40,1))],
                         [sg.Listbox(values=self.engine_list, size=(48,6),
-                                    bind_return_key = True, key='engine_file_k')],
+                                    key='engine_file_k')],
                         [sg.T('Threads', size=(12, 1)), 
                          sg.Spin([t for t in range(1, 9)], initial_value=self.threads,
                                   size=(8, 1), key='threads_k')],
@@ -1949,12 +1959,10 @@ def main_loop(self):
                         self.threads = min(MAX_THREADS, max(MIN_THREADS, threads_value))
 
                         # In case the user did not select an engine and presses OK
-                        try:
-                            self.engine_file = v['engine_file_k'][0]
-                            engine_id_name = self.get_engine_id_name()
-                            self.update_engine_list()
-                        except:
-                            pass
+                        self.engine_file = v['engine_file_k'][0]
+                        self.get_engine_id_name()
+                        engine_id_name = self.opp_eng_id_name
+                        self.update_engine_list()
                         break
 
                 self.window.Enable()