Add a mechanism for logging errors instead of swallowing exceptions

pudb/debugger.py

@@ -2613,7 +2613,8 @@ class DebuggerUI(FrameVarInfoKeeper):
                 try:
                     class_name = frame.f_locals["self"].__class__.__name__
                 except Exception:
-                    pass
+                    from pudb.lowlevel import ui_log
+                    ui_log.exception('Failed to determine class name')
 
             return StackFrame(frame is self.debugger.curframe,
                     code.co_name, class_name,

pudb/lowlevel.py

@@ -28,6 +28,26 @@ THE SOFTWARE.
 
 from pudb.py3compat import PY3, text_type
 
+import logging
+
+ui_formatter = logging.Formatter(
+    fmt='\n*** Pudb UI Exception Encountered: %(message)s ***\n'
+)
+ui_handler = logging.StreamHandler()
+ui_handler.setFormatter(ui_formatter)
+ui_log = logging.getLogger('ui')
+ui_log.setLevel(logging.CRITICAL)
+ui_log.addHandler(ui_handler)
+
+settings_formatter = logging.Formatter(
+    fmt='\n*** Pudb Settings Exception Encountered: %(message)s ***\n'
+)
+settings_handler = logging.StreamHandler()
+settings_handler.setFormatter(settings_formatter)
+settings_log = logging.getLogger('settings')
+settings_log.setLevel(logging.CRITICAL)
+settings_log.addHandler(settings_handler)
+
 
 # {{{ breakpoint validity
 

pudb/run.py

@@ -15,17 +15,27 @@ def main():
     #    python -m pudb -m http.server -h
     # where the -h will be passed to the http.server module
     parser.add_argument("-m", "--module", action='store_true',
-                      help="Debug as module or package instead of as a script")
+                        help="Debug as module or package instead of as a script")
 
+    parser.add_argument("-le", "--log-errors", action='store_true',
+                        help="If an unexpected exception is encountered, "
+                             "log the exception information to stderr",
+                        default=False)
     parser.add_argument("--pre-run", metavar="COMMAND",
-            help="Run command before each program run",
-            default="")
+                        help="Run command before each program run",
+                        default="")
     parser.add_argument('script_args', nargs=argparse.REMAINDER,
                         help="Arguments to pass to script or module")
 
     options = parser.parse_args()
     args = options.script_args
 
+    if options.log_errors:
+        import logging
+        from pudb.lowlevel import ui_log, settings_log
+        ui_log.setLevel(logging.ERROR)
+        settings_log.setLevel(logging.ERROR)
+
     options_kwargs = {
         'pre_run': options.pre_run,
         'steal_output': options.steal_output,

pudb/settings.py

@@ -25,12 +25,12 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 """
 
-
 import os
 import sys
 
 from pudb.py3compat import ConfigParser
-from pudb.lowlevel import lookup_module, get_breakpoint_invalid_reason
+from pudb.lowlevel import (lookup_module, get_breakpoint_invalid_reason,
+                           settings_log)
 
 # minor LGPL violation: stolen from python-xdg
 
@@ -85,7 +85,7 @@ def load_config():
         if cparser.has_section(CONF_SECTION):
             conf_dict.update(dict(cparser.items(CONF_SECTION)))
     except Exception:
-        pass
+        settings_log.exception('Failed to load config')
 
     conf_dict.setdefault("shell", "internal")
     conf_dict.setdefault("theme", "classic")
@@ -121,7 +121,7 @@ def load_config():
             else:
                 conf_dict[name] = True
         except Exception:
-            pass
+            settings_log.exception('Failed to process config')
 
     normalize_bool_inplace("line_numbers")
     normalize_bool_inplace("wrap_variables")
@@ -148,7 +148,7 @@ def save_config(conf_dict):
         cparser.write(outf)
         outf.close()
     except Exception:
-        pass
+        settings_log.exception('Failed to save config')
 
 
 def edit_config(ui, conf_dict):

pudb/var_view.py

@@ -33,6 +33,8 @@ THE SOFTWARE.
 import urwid
 import inspect
 
+from pudb.lowlevel import ui_log
+
 try:
     import numpy
     HAVE_NUMPY = 1
@@ -285,7 +287,7 @@ def type_stringifier(value):
         try:
             return text_type(value)
         except Exception:
-            pass
+            ui_log.exception('string safe type stringifier failed')
 
     elif hasattr(type(value), "safely_stringify_for_pudb"):
         try:
@@ -293,7 +295,7 @@ def type_stringifier(value):
             # and return nonsense.
             result = value.safely_stringify_for_pudb()
         except Exception:
-            pass
+            ui_log.exception('safely_stringify_for_pudb call failed')
         else:
             if isinstance(result, string_types):
                 return text_type(result)
@@ -371,6 +373,7 @@ class ValueWalker:
                 # repr() on a random object.
                 displayed_value = type_stringifier(value) \
                                 + " (!! %s error !!)" % iinfo.display_type
+                ui_log.exception('stringifier failed')
 
             if iinfo.show_detail:
                 if iinfo.access_level == "public":
@@ -414,21 +417,27 @@ class ValueWalker:
                     key_it = value.keys()
                 else:
                     key_it = value.iterkeys()
-            except Exception:
+            except AttributeError:
+                # keys or iterkeys doesn't exist, not worth mentioning!
                 pass
+            except Exception:
+                ui_log.exception('Failed to obtain key iterator')
 
             if key_it is None:
                 try:
                     len_value = len(value)
-                except Exception:
+                except TypeError:
+                    # no __len__ defined on the value, not worth mentioning!
                     pass
+                except Exception:
+                    ui_log.exception('Failed to determine container length')
                 else:
                     try:
                         value[0]
                     except IndexError:
                         key_it = []
                     except Exception:
-                        pass
+                        ui_log.exception('Item is not iterable')
                     else:
                         key_it = xrange(len_value)
 
@@ -456,7 +465,7 @@ class ValueWalker:
             try:
                 key_its.append(dir(value))
             except Exception:
-                pass
+                ui_log.exception('Failed to lookup attributes')
 
             keys = [key
                     for ki in key_its