Merge pull request awesto#226 from jrief/add-callable

Add callable

shop/models_bases/__init__.py

@@ -419,7 +419,7 @@ def set_billing_address(self, billing_address):
         e.g. you can copy address instance and save FK to it in your order
         class.
         """
-        if  hasattr(billing_address, 'as_text'):
+        if hasattr(billing_address, 'as_text') and callable(billing_address.as_text):
             self.billing_address_text = billing_address.as_text()
             self.save()
 
@@ -431,7 +431,7 @@ def set_shipping_address(self, shipping_address):
         e.g. you can copy address instance and save FK to it in your order
         class.
         """
-        if hasattr(shipping_address, 'as_text'):
+        if hasattr(shipping_address, 'as_text') and callable(shipping_address.as_text):
             self.shipping_address_text = shipping_address.as_text()
             self.save()