This contains a number of things:

1) Improve the documentation of the SSL module, with a fuller
   explanation of certificate usage, another reference, proper
   formatting of this and that.

2) Fix Windows bug in ssl.py, and general bug in sslsocket.close().
   Remove some unused code from ssl.py.  Allow accept() to be called on
   sslsocket sockets.

3) Use try-except-else in import of ssl in socket.py.  Deprecate use of
   socket.ssl().

4) Remove use of socket.ssl() in every library module, except for
   test_socket_ssl.py and test_ssl.py.

Lib/imaplib.py

@@ -1111,94 +1111,99 @@ class IMAP4:
 
 
 
-class IMAP4_SSL(IMAP4):
+try:
+    import ssl
+except ImportError:
+    pass
+else:
+    class IMAP4_SSL(IMAP4):
 
-    """IMAP4 client class over SSL connection
+        """IMAP4 client class over SSL connection
 
-    Instantiate with: IMAP4_SSL([host[, port[, keyfile[, certfile]]]])
+        Instantiate with: IMAP4_SSL([host[, port[, keyfile[, certfile]]]])
 
-            host - host's name (default: localhost);
-            port - port number (default: standard IMAP4 SSL port).
-            keyfile - PEM formatted file that contains your private key (default: None);
-            certfile - PEM formatted certificate chain file (default: None);
+                host - host's name (default: localhost);
+                port - port number (default: standard IMAP4 SSL port).
+                keyfile - PEM formatted file that contains your private key (default: None);
+                certfile - PEM formatted certificate chain file (default: None);
 
-    for more documentation see the docstring of the parent class IMAP4.
-    """
-
-
-    def __init__(self, host = '', port = IMAP4_SSL_PORT, keyfile = None, certfile = None):
-        self.keyfile = keyfile
-        self.certfile = certfile
-        IMAP4.__init__(self, host, port)
-
-
-    def open(self, host = '', port = IMAP4_SSL_PORT):
-        """Setup connection to remote server on "host:port".
-            (default: localhost:standard IMAP4 SSL port).
-        This connection will be used by the routines:
-            read, readline, send, shutdown.
+        for more documentation see the docstring of the parent class IMAP4.
         """
-        self.host = host
-        self.port = port
-        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        self.sock.connect((host, port))
-        self.sslobj = socket.ssl(self.sock, self.keyfile, self.certfile)
 
 
-    def read(self, size):
-        """Read 'size' bytes from remote."""
-        # sslobj.read() sometimes returns < size bytes
-        chunks = []
-        read = 0
-        while read < size:
-            data = self.sslobj.read(size-read)
-            read += len(data)
-            chunks.append(data)
-
-        return ''.join(chunks)
+        def __init__(self, host = '', port = IMAP4_SSL_PORT, keyfile = None, certfile = None):
+            self.keyfile = keyfile
+            self.certfile = certfile
+            IMAP4.__init__(self, host, port)
 
 
-    def readline(self):
-        """Read line from remote."""
-        # NB: socket.ssl needs a "readline" method, or perhaps a "makefile" method.
-        line = []
-        while 1:
-            char = self.sslobj.read(1)
-            line.append(char)
-            if char == "\n": return ''.join(line)
+        def open(self, host = '', port = IMAP4_SSL_PORT):
+            """Setup connection to remote server on "host:port".
+                (default: localhost:standard IMAP4 SSL port).
+            This connection will be used by the routines:
+                read, readline, send, shutdown.
+            """
+            self.host = host
+            self.port = port
+            self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.sock.connect((host, port))
+            self.sslobj = ssl.sslsocket(self.sock, self.keyfile, self.certfile)
 
 
-    def send(self, data):
-        """Send data to remote."""
-        # NB: socket.ssl needs a "sendall" method to match socket objects.
-        bytes = len(data)
-        while bytes > 0:
-            sent = self.sslobj.write(data)
-            if sent == bytes:
-                break    # avoid copy
-            data = data[sent:]
-            bytes = bytes - sent
+        def read(self, size):
+            """Read 'size' bytes from remote."""
+            # sslobj.read() sometimes returns < size bytes
+            chunks = []
+            read = 0
+            while read < size:
+                data = self.sslobj.read(size-read)
+                read += len(data)
+                chunks.append(data)
+
+            return ''.join(chunks)
 
 
-    def shutdown(self):
-        """Close I/O established in "open"."""
-        self.sock.close()
+        def readline(self):
+            """Read line from remote."""
+            # NB: socket.ssl needs a "readline" method, or perhaps a "makefile" method.
+            line = []
+            while 1:
+                char = self.sslobj.read(1)
+                line.append(char)
+                if char == "\n": return ''.join(line)
 
 
-    def socket(self):
-        """Return socket instance used to connect to IMAP4 server.
-
-        socket = <instance>.socket()
-        """
-        return self.sock
+        def send(self, data):
+            """Send data to remote."""
+            # NB: socket.ssl needs a "sendall" method to match socket objects.
+            bytes = len(data)
+            while bytes > 0:
+                sent = self.sslobj.write(data)
+                if sent == bytes:
+                    break    # avoid copy
+                data = data[sent:]
+                bytes = bytes - sent
 
 
-    def ssl(self):
-        """Return SSLObject instance used to communicate with the IMAP4 server.
+        def shutdown(self):
+            """Close I/O established in "open"."""
+            self.sock.close()
 
-        ssl = <instance>.socket.ssl()
-        """
-        return self.sslobj
+
+        def socket(self):
+            """Return socket instance used to connect to IMAP4 server.
+
+            socket = <instance>.socket()
+            """
+            return self.sock
+
+
+        def ssl(self):
+            """Return SSLObject instance used to communicate with the IMAP4 server.
+
+            ssl = <instance>.socket.ssl()
+            """
+            return self.sslobj