Simplify KeyError fallbacks that don't need to be lazy (#2330)

CHANGES.txt

@@ -14,7 +14,7 @@ https://mhammond.github.io/pywin32_installers.html.
 Coming in build 309, as yet unreleased
 --------------------------------------
 
-* Improved handling of dict iterations (removes Python 2 support code, small general speed improvement) (#2332, @Avasam)
+* Improved handling of dict iterations and fallbacks (removes Python 2 support code, small general speed improvement) (#2332, #2330, @Avasam)
 * Fixed "Open GL Demo" (`Pythonwin/pywin/Demos/openGLDemo.py`) and restore "Font" demo in `Pythonwin/pywin/Demos/guidemo.py` (#2345, @Avasam)
 
 Build 308, released 2024-10-12

Pythonwin/pywin/Demos/cmdserver.py

@@ -37,10 +37,7 @@ def unregister(self):
 
     def getwriter(self):
         "Return the current thread's writer, default sys.stdout"
-        try:
-            return self.writers[_thread.get_ident()]
-        except KeyError:
-            return self.origStdOut
+        self.writers.get(_thread.get_ident(), self.origStdOut)
 
     def write(self, str):
         "Write to the current thread's writer, default sys.stdout"

com/win32com/client/combrowse.py

@@ -265,10 +265,7 @@ class HLITypeLibEntry(HLICOM):
     def GetText(self):
         tlb, index = self.myobject
         name, doc, ctx, helpFile = tlb.GetDocumentation(index)
-        try:
-            typedesc = HLITypeKinds[tlb.GetTypeInfoType(index)][1]
-        except KeyError:
-            typedesc = "Unknown!"
+        typedesc = HLITypeKinds.get(tlb.GetTypeInfoType(index), (None, "Unknown!"))[1]
         return name + " - " + typedesc
 
     def GetSubList(self):
@@ -448,10 +445,7 @@ def GetText(self):
 
     def MakeReturnTypeName(self, typ):
         justtyp = typ & pythoncom.VT_TYPEMASK
-        try:
-            typname = self.vartypes[justtyp]
-        except KeyError:
-            typname = "?Bad type?"
+        typname = self.vartypes.get(justtyp, "?Bad type?")
         for flag, desc in self.type_flags:
             if flag & typ:
                 typname = f"{desc}({typname})"
@@ -493,15 +487,9 @@ def GetSubList(self):
                 val += f" (Default={default})"
             ret.append(browser.MakeHLI(val, "Argument"))
 
-        try:
-            fkind = self.funckinds[fd[3]]
-        except KeyError:
-            fkind = "Unknown"
+        fkind = self.funckinds.get(fd[3], "Unknown")
         ret.append(browser.MakeHLI(fkind, "Function Kind"))
-        try:
-            ikind = self.invokekinds[fd[4]]
-        except KeyError:
-            ikind = "Unknown"
+        ikind = self.invokekinds.get([fd[4]], "Unknown")
         ret.append(browser.MakeHLI(ikind, "Invoke Kind"))
         # 5 = call conv
         # 5 = offset vtbl

com/win32com/servers/dictionary.py

@@ -85,10 +85,7 @@ def _invokeex_(self, dispid, lcid, wFlags, args, kwargs, serviceProvider):
             if wFlags & (DISPATCH_METHOD | DISPATCH_PROPERTYGET):
                 if l > 1:
                     raise COMException(scode=winerror.DISP_E_BADPARAMCOUNT)
-                try:
-                    return self._obj_[key]
-                except KeyError:
-                    return None  # unknown keys return None (VT_NULL)
+                return self._obj_.get(key)  # unknown keys return None (VT_NULL)
 
             if l != 2:
                 raise COMException(scode=winerror.DISP_E_BADPARAMCOUNT)

com/win32com/test/testExchange.py

@@ -86,10 +86,7 @@ def TestUser(session):
     print("User has %d fields" % len(fields))
     for f in range(len(fields)):
         field = fields[f + 1]
-        try:
-            id = PropTagsById[field.ID]
-        except KeyError:
-            id = field.ID
+        id = PropTagsById.get(field.ID, field.ID)
         print(f"{field.Name}/{id}={field.Value}")
 
 

com/win32comext/axdebug/adb.py

@@ -19,12 +19,7 @@ def fnull(*args):
     pass
 
 
-try:
-    os.environ["DEBUG_AXDEBUG"]
-    debugging = 1
-except KeyError:
-    debugging = 0
-
+debugging = "DEBUG_AXDEBUG" in os.environ
 traceenter = fnull  # trace enter of functions
 tracev = fnull  # verbose trace
 

com/win32comext/axdebug/codecontainer.py

@@ -197,7 +197,6 @@ def GetCodeContextAtPosition(self, charPos):
         charPos = self.GetPositionOfLine(lineNo)
         try:
             cc = self.codeContexts[charPos]
-        # trace(" GetContextOfPos using existing")
         except KeyError:
             cc = self._MakeContextAtPosition(charPos)
             self.codeContexts[charPos] = cc

com/win32comext/axdebug/util.py

@@ -10,11 +10,7 @@
 import winerror
 from win32com.server.exception import COMException
 
-try:
-    os.environ["DEBUG_AXDEBUG"]
-    debugging = 1
-except KeyError:
-    debugging = 0
+debugging = "DEBUG_AXDEBUG" in os.environ
 
 
 def trace(*args):

com/win32comext/axscript/client/debug.py

@@ -12,11 +12,7 @@
 from win32com.server.exception import COMException
 from win32com.util import IIDToInterfaceName
 
-try:
-    os.environ["DEBUG_AXDEBUG"]
-    debuggingTrace = 1  # Should we print "trace" output?
-except KeyError:
-    debuggingTrace = 0
+debuggingTrace = "DEBUG_AXDEBUG" in os.environ  # Should we print "trace" output?
 
 
 def trace(*args):

com/win32comext/axscript/client/pyscript.py

@@ -160,15 +160,12 @@ def Register(self):
         self.attributeObject = NamedScriptAttribute(self)
         if self.dispatch:
             # Need to avoid the new Python "lazy" dispatch behaviour.
+            olerepr, clsid = None
             try:
                 engine = self.GetEngine()
-                olerepr = clsid = None
                 typeinfo = self.dispatch.GetTypeInfo()
                 clsid = typeinfo.GetTypeAttr()[0]
-                try:
-                    olerepr = engine.mapKnownCOMTypes[clsid]
-                except KeyError:
-                    pass
+                olerepr = engine.mapKnownCOMTypes.get(clsid)
             except pythoncom.com_error:
                 typeinfo = None
             if olerepr is None:

setup.py

@@ -820,21 +820,17 @@ def swig_sources(self, sources, ext=None):
             else:
                 swig_cmd.append("-DSWIG_PY32BIT")
             target = swig_targets[source]
-            try:
-                interface_parent = swig_interface_parents[
-                    os.path.basename(os.path.splitext(source)[0])
-                ]
-            except KeyError:
-                # "normal" swig file - no special win32 issues.
-                pass
-            else:
-                # Using win32 extensions to SWIG for generating COM classes.
-                if interface_parent is not None:
-                    # generating a class, not a module.
-                    swig_cmd.append("-pythoncom")
-                    if interface_parent:
-                        # A class deriving from other than the default
-                        swig_cmd.extend(["-com_interface_parent", interface_parent])
+            interface_parent = swig_interface_parents.get(
+                os.path.basename(os.path.splitext(source)[0]),
+                None,  # "normal" swig file - no special win32 issues.
+            )
+            # Using win32 extensions to SWIG for generating COM classes.
+            if interface_parent is not None:
+                # generating a class, not a module.
+                swig_cmd.append("-pythoncom")
+                if interface_parent:
+                    # A class deriving from other than the default
+                    swig_cmd.extend(["-com_interface_parent", interface_parent])
 
             # This 'newer' check helps Python 2.2 builds, which otherwise
             # *always* regenerate the .cpp files, meaning every future

win32/Lib/netbios.py

@@ -210,10 +210,7 @@ def __init__(self, items):
     def _pack(self):
         vals = []
         for format, name in self._items:
-            try:
-                vals.append(self.__dict__[name])
-            except KeyError:
-                vals.append(None)
+            vals.append(self.__dict__.get(name))
 
         self._buffer_[:] = struct.pack(*(self._format,) + tuple(vals))
 

win32/Lib/win32serviceutil.py

@@ -751,10 +751,9 @@ def HandleCommandLine(
                 "delayed": win32service.SERVICE_AUTO_START,  ## ChangeServiceConfig2 called later
                 "disabled": win32service.SERVICE_DISABLED,
             }
-            try:
-                startup = map[val.lower()]
-            except KeyError:
-                print("'%s' is not a valid startup option" % val)
+            startup = map.get(val.lower())
+            if not startup:
+                print(f"{val!r} is not a valid startup option")
             if val.lower() == "delayed":
                 delayedstart = True
             elif val.lower() == "auto":

win32/Lib/win32timezone.py

@@ -989,6 +989,7 @@ def get(self, key, default=None):
         If default is not given, it defaults to None, so that this method
         never raises a KeyError.
         """
+        # Necessary to use our own __getitem__ and not dict's
         try:
             return self[key]
         except KeyError: