Coding style.

- Use a context manager for signal_handlers.

eris/fill3.py

@@ -479,26 +479,31 @@ def on_terminal_input(screen_widget):
         return screen_widget.on_input_event(code)  # keyboard
 
 
+@contextlib.contextmanager
+def signal_handler(loop, signal_, func):
+    loop.add_signal_handler(signal_, func)
+    try:
+        yield
+    finally:
+        loop.remove_signal_handler(signal_)
+
+
 @contextlib.contextmanager
 def context(loop, appearance_changed_event, screen_widget, exit_loop=None):
     appearance_changed_event.set()
     if exit_loop is None:
         exit_loop = loop.stop
-    loop.add_signal_handler(signal.SIGWINCH, lambda: draw_screen(screen_widget))
+    with signal_handler(loop, signal.SIGWINCH,
-    loop.add_signal_handler(signal.SIGINT, exit_loop)
+                        lambda: draw_screen(screen_widget)), \
-    loop.add_signal_handler(signal.SIGTERM, exit_loop)
+         signal_handler(loop, signal.SIGINT, exit_loop), \
-    try:
+         signal_handler(loop, signal.SIGTERM, exit_loop), \
-        with terminal.alternate_buffer(), terminal.interactive(), \
+         terminal.alternate_buffer(), terminal.interactive(), \
-             terminal.mouse_tracking():
+         terminal.mouse_tracking():
-            loop.add_reader(sys.stdin, on_terminal_input, screen_widget)
+        loop.add_reader(sys.stdin, on_terminal_input, screen_widget)
-            try:
+        try:
-                yield
+            yield
-            finally:
+        finally:
-                loop.remove_reader(sys.stdin)
+            loop.remove_reader(sys.stdin)
-    finally:
-        loop.remove_signal_handler(signal.SIGWINCH)
-        loop.remove_signal_handler(signal.SIGINT)
-        loop.remove_signal_handler(signal.SIGTERM)
 
 
 ##########################