simplify and modernize updatecache()

Lib/linecache.py

@@ -72,13 +72,13 @@ def updatecache(filename, module_globals=None):
 
     if filename in cache:
         del cache[filename]
-    if not filename or filename[0] + filename[-1] == '<>':
+    if not filename or (filename.startswith('<') and filename.endswith('>')):
         return []
 
     fullname = filename
     try:
         stat = os.stat(fullname)
-    except os.error, msg:
+    except OSError:
         basename = filename
 
         # Try for a __loader__, if available
@@ -115,8 +115,7 @@ def updatecache(filename, module_globals=None):
                 fullname = os.path.join(dirname, basename)
             except (TypeError, AttributeError):
                 # Not sufficiently string-like to do anything useful with.
-                pass
-            else:
+                continue
             try:
                 stat = os.stat(fullname)
                 break
@@ -125,10 +124,9 @@ def updatecache(filename, module_globals=None):
         else:
             return []
     try:
-        fp = open(fullname, 'rU')
+        with open(fullname, 'rU') as fp:
             lines = fp.readlines()
-        fp.close()
-    except IOError, msg:
+    except IOError:
         return []
     if lines and not lines[-1].endswith('\n'):
         lines[-1] += '\n'