Update preferred method for reading/writing messages from files

test/test_regression.py

@@ -9,7 +9,7 @@ this_dir = os.path.dirname(__file__)
 def addressbook():
      return capnp.load(os.path.join(this_dir, 'addressbook.capnp'))
 
-def test_addressbook(addressbook):
+def test_addressbook_message_classes(addressbook):
     def writeAddressBook(fd):
         message = capnp.MallocMessageBuilder()
         addressBook = message.initRoot(addressbook.AddressBook)
@@ -67,6 +67,63 @@ def test_addressbook(addressbook):
     f = open('example', 'r')
     printAddressBook(f.fileno())
 
+def test_addressbook(addressbook):
+    def writeAddressBook(file):
+        addresses = addressbook.AddressBook.newMessage()
+        people = addresses.init('people', 2)
+
+        alice = people[0]
+        alice.id = 123
+        alice.name = 'Alice'
+        alice.email = 'alice@example.com'
+        alicePhones = alice.init('phones', 1)
+        alicePhones[0].number = "555-1212"
+        alicePhones[0].type = 'mobile'
+        alice.employment.school = "MIT"
+
+        bob = people[1]
+        bob.id = 456
+        bob.name = 'Bob'
+        bob.email = 'bob@example.com'
+        bobPhones = bob.init('phones', 2)
+        bobPhones[0].number = "555-4567"
+        bobPhones[0].type = 'home'
+        bobPhones[1].number = "555-7654"
+        bobPhones[1].type = 'work'
+        bob.employment.unemployed = None
+
+        addresses.writeTo(file)
+
+
+    def printAddressBook(file):
+        addresses = addressbook.AddressBook.readFrom(file)
+
+        for person in addresses.people:
+            print(person.name, ':', person.email)
+            for phone in person.phones:
+                print(phone.type, ':', phone.number)
+
+            which = person.employment.which()
+            print(which)
+
+            if which == 'unemployed':
+                print('unemployed')
+            elif which == 'employer':
+                print('employer:', person.employment.employer)
+            elif which == 'school':
+                print('student at:', person.employment.school)
+            elif which == 'selfEmployed':
+                print('self employed')
+            print()
+
+
+    f = open('example', 'w')
+    writeAddressBook(f)
+
+    f = open('example', 'r')
+    printAddressBook(f)
+
+
 @pytest.fixture
 def all_types():
     return capnp.load(os.path.join(this_dir, 'all-types.capnp'))