load transports on demand

sendgrid/sendgrid.py

@@ -1,10 +1,19 @@
-from transport import smtp, web
+def memoize(f):
+    """
+    Memoization decorator
+    """
+    cache= {}
+    def func(*args):
+        if args not in cache:
+            cache[args] = f(*args)
+        return cache[args]
+    return func
+
 
 class Sendgrid(object):
     """
     Sendgrid API
     """
-
     def __init__(self, username, password, secure=True):
         """
         Construct Sendgrid API object
@@ -14,6 +23,26 @@ def __init__(self, username, password, secure=True):
             password: Sendgrid password
             ssl: Use SSL
         """
+        self.username = username
+        self.password = password
+        self.secure = secure
+
 
-        self.web = web.Http(username, password, secure)
-        self.smtp = smtp.Smtp(username, password, secure)
+    @property
+    @memoize
+    def web(self):
+        """
+        Return web transport
+        """
+        from transport import web
+        return web.Http(self.username, self.password, self.secure)
+
+
+    @property
+    @memoize
+    def smtp(self):
+        """
+        Return smtp transport
+        """
+        from transport import smtp
+        return smtp.Smtp(self.username, self.password, self.secure)