No longer using stderr and self.data together to determine truthiness of a CommandResult.

Either self.data is used or if that's not possible, then self.stderr is used.
This provided applications the ability to print to stderr even if an error didn't occur.

1 files changed, 10 insertions, 3 deletions

diff --git a/cmd2/pyscript_bridge.py b/cmd2/pyscript_bridge.py
index 2002ca6d..dcfd9116 100644
--- a/cmd2/pyscript_bridge.py
+++ b/cmd2/pyscript_bridge.py
@@ -33,9 +33,16 @@ class CommandResult(namedtuple_with_defaults('CommandResult', ['stdout', 'stderr
 
     NOTE: Named tuples are immutable.  So the contents are there for access, not for modification.
     """
-    def __bool__(self):
-        """If stderr is None and data is not None the command is considered a success"""
-        return not self.stderr and self.data is not None
+    def __bool__(self) -> bool:
+        """Returns True if the command succeeded, otherwise False"""
+
+        # If data has a __bool__ method, then call it to determine success of command
+        if self.data is not None and callable(getattr(self.data, '__bool__', None)):
+            return True if self.data else False
+
+        # Otherwise check if stderr was filled out
+        else:
+            return not self.stderr
 
 
 def _exec_cmd(cmd2_app, func: Callable, echo: bool) -> CommandResult: