Use an if instead of a try statement

maxnordlund · sebastinas · commit c58a933746df · 2017-07-08T10:43:47.000+02:00
diff --git a/bpython/curtsiesfrontend/repl.py b/bpython/curtsiesfrontend/repl.py
@@ -11,6 +11,7 @@
 import subprocess
 import sys
 import tempfile
+import threading
 import time
 import unicodedata
 from six.moves import range
@@ -532,12 +533,10 @@ def __enter__(self):
         self.orig_sigwinch_handler = signal.getsignal(signal.SIGWINCH)
         self.orig_sigtstp_handler = signal.getsignal(signal.SIGTSTP)
 
-        try:
+        if isinstance(threading.current_thread(), threading._MainThread):
+            # This turns off resize detection and ctrl-z suspension.
             signal.signal(signal.SIGWINCH, self.sigwinch_handler)
             signal.signal(signal.SIGTSTP, self.sigtstp_handler)
-        except ValueError:
-            pass # Ignore "signal only works in main thread"
-            # This turns off resize detection and ctrl-z suspension.
 
         self.orig_meta_path = sys.meta_path
         if self.watcher:
@@ -551,12 +550,10 @@ def __exit__(self, *args):
         sys.stdout = self.orig_stdout
         sys.stderr = self.orig_stderr
 
-        try:
+        if isinstance(threading.current_thread(), threading._MainThread):
+            # This turns off resize detection and ctrl-z suspension.
             signal.signal(signal.SIGWINCH, self.orig_sigwinch_handler)
             signal.signal(signal.SIGTSTP, self.orig_sigtstp_handler)
-        except ValueError:
-            pass # Ignore "signal only works in main thread"
-            # This turns off resize detection and ctrl-z suspension.
 
         sys.meta_path = self.orig_meta_path
 
