Replace boolean test with is None.

Lib/sgmllib.py

@@ -479,7 +479,7 @@ def close(self):
 def test(args = None):
     import sys
 
-    if not args:
+    if args is None:
         args = sys.argv[1:]
 
     if args and args[0] == '-s':

Lib/shlex.py

@@ -12,7 +12,7 @@
 class shlex:
     "A lexical analyzer class for simple shell-like syntaxes."
     def __init__(self, instream=None, infile=None):
-        if instream:
+        if instream is not None:
             self.instream = instream
             self.infile = infile
         else:
@@ -47,7 +47,7 @@ def push_source(self, newstream, newfile=None):
         self.instream = newstream
         self.lineno = 1
         if self.debug:
-            if newfile:
+            if newfile is not None:
                 print 'shlex: pushing to file %s' % (self.infile,)
             else:
                 print 'shlex: pushing to stream %s' % (self.instream,)
@@ -188,9 +188,9 @@ def sourcehook(self, newfile):
 
     def error_leader(self, infile=None, lineno=None):
         "Emit a C-compiler-like, Emacs-friendly error-message leader."
-        if not infile:
+        if infile is None:
             infile = self.infile
-        if not lineno:
+        if lineno is None:
             lineno = self.lineno
         return "\"%s\", line %d: " % (infile, lineno)
 

Lib/shutil.py

@@ -122,7 +122,7 @@ def rmtree(path, ignore_errors=0, onerror=None):
             exc = sys.exc_info()
             if ignore_errors:
                 pass
-            elif onerror:
+            elif onerror is not None:
                 onerror(cmd[0], cmd[1], exc)
             else:
                 raise exc[0], (exc[1][0], exc[1][1] + ' removing '+cmd[1])

Lib/smtplib.py

@@ -236,7 +236,7 @@ def __init__(self, host = '', port = 0, local_hostname = None):
             (code, msg) = self.connect(host, port)
             if code != 220:
                 raise SMTPConnectError(code, msg)
-        if local_hostname:
+        if local_hostname is not None:
             self.local_hostname = local_hostname
         else:
             # RFC 2821 says we should use the fqdn in the EHLO/HELO verb, and

Lib/sre_compile.py

@@ -145,7 +145,7 @@ def fixup(literal, flags=flags):
 def _compile_charset(charset, flags, code, fixup=None):
     # compile charset subprogram
     emit = code.append
-    if not fixup:
+    if fixup is None:
         fixup = lambda x: x
     for op, av in _optimize_charset(charset, fixup):
         emit(OPCODES[op])

Lib/sre_parse.py

@@ -80,7 +80,7 @@ def __init__(self):
     def opengroup(self, name=None):
         gid = self.groups
         self.groups = gid + 1
-        if name:
+        if name is not None:
             ogid = self.groupdict.get(name, None)
             if ogid is not None:
                 raise error, ("redefinition of group name %s as group %d; "
@@ -97,7 +97,7 @@ class SubPattern:
     # a subpattern, in intermediate form
     def __init__(self, pattern, data=None):
         self.pattern = pattern
-        if not data:
+        if data is None:
             data = []
         self.data = data
         self.width = None