5 files changed, 19 insertions, 18 deletions

diff --git a/glucometerutils/common.py b/glucometerutils/common.py
index 9350983..4c6e115 100644
--- a/glucometerutils/common.py
+++ b/glucometerutils/common.py
@@ -17,9 +17,10 @@ class Unit(enum.Enum):
   MMOL_L = 'mmol/L'
 
 # Constants for meal information
-NO_MEAL = ''
-BEFORE_MEAL = 'Before Meal'
-AFTER_MEAL = 'After Meal'
+class Meal(enum.Enum):
+  NONE = ''
+  BEFORE = 'Before Meal'
+  AFTER = 'After Meal'
 
 # Constants for measure method
 BLOOD_SAMPLE = 'blood sample'
@@ -52,7 +53,7 @@ _ReadingBase = collections.namedtuple(
   '_ReadingBase', ['timestamp', 'value', 'comment', 'measure_method'])
 
 class GlucoseReading(_ReadingBase):
-  def __new__(cls, timestamp, value, meal=NO_MEAL, comment='',
+  def __new__(cls, timestamp, value, meal=Meal.NONE, comment='',
               measure_method=BLOOD_SAMPLE):
     """Constructor for the glucose reading object.
 
@@ -85,8 +86,8 @@ class GlucoseReading(_ReadingBase):
   def as_csv(self, unit):
     """Returns the reading as a formatted comma-separated value string."""
     return '"%s","%.2f","%s","%s","%s"' % (
-      self.timestamp, self.get_value_as(unit), self.meal, self.measure_method,
-      self.comment)
+      self.timestamp, self.get_value_as(unit), self.meal.value,
+      self.measure_method, self.comment)
 
 class KetoneReading(_ReadingBase):
   def __new__(cls, timestamp, value, comment='', **kwargs):
diff --git a/glucometerutils/drivers/accuchek_reports.py b/glucometerutils/drivers/accuchek_reports.py
index 03eeddd..d55ac0f 100644
--- a/glucometerutils/drivers/accuchek_reports.py
+++ b/glucometerutils/drivers/accuchek_reports.py
@@ -117,11 +117,11 @@ class Device(object):
     if record[_AFTER_MEAL_CSV_KEY] and record[_BEFORE_MEAL_CSV_KEY]:
       raise InvalidResponse('Reading cannot be before and after meal.')
     elif record[_AFTER_MEAL_CSV_KEY]:
-      return common.AFTER_MEAL
+      return common.Meal.AFTER
     elif record[_BEFORE_MEAL_CSV_KEY]:
-      return common.BEFORE_MEAL
+      return common.Meal.BEFORE
     else:
-      return common.NO_MEAL
+      return common.Meal.NONE
 
   def get_readings(self):
     for record in self._get_records_reader():
diff --git a/glucometerutils/drivers/otultra2.py b/glucometerutils/drivers/otultra2.py
index f44bc15..762991e 100644
--- a/glucometerutils/drivers/otultra2.py
+++ b/glucometerutils/drivers/otultra2.py
@@ -27,9 +27,9 @@ from glucometerutils.support import serial
 
 # The following two hashes are taken directly from LifeScan's documentation
 _MEAL_CODES = {
-  'N': common.NO_MEAL,
-  'B': common.BEFORE_MEAL,
-  'A': common.AFTER_MEAL,
+  'N': common.Meal.NONE,
+  'B': common.Meal.BEFORE,
+  'A': common.Meal.AFTER,
 }
 
 _COMMENT_CODES = {
diff --git a/glucometerutils/drivers/otverio2015.py b/glucometerutils/drivers/otverio2015.py
index c416678..5925a58 100644
--- a/glucometerutils/drivers/otverio2015.py
+++ b/glucometerutils/drivers/otverio2015.py
@@ -76,9 +76,9 @@ _READ_RECORD_REQUEST_SUFFIX = b'\x00'
 _MEMORY_ERASE_REQUEST = b'\x04\x1a'
 
 _MEAL_CODES = {
-  0x00: common.NO_MEAL,
-  0x01: common.BEFORE_MEAL,
-  0x02: common.AFTER_MEAL,
+  0x00: common.Meal.NONE,
+  0x01: common.Meal.BEFORE,
+  0x02: common.Meal.AFTER,
 }
 
 def _extract_message(register):
diff --git a/glucometerutils/drivers/sdcodefree.py b/glucometerutils/drivers/sdcodefree.py
index 4939361..4a375bd 100644
--- a/glucometerutils/drivers/sdcodefree.py
+++ b/glucometerutils/drivers/sdcodefree.py
@@ -65,9 +65,9 @@ _ReadingRecord = collections.namedtuple(
 _STRUCT_READING = struct.Struct('>BBBBBBBHB')
 
 _MEAL_FLAG = {
-    0x00: common.NO_MEAL,
-    0x10: common.BEFORE_MEAL,
-    0x20: common.AFTER_MEAL
+    0x00: common.Meal.NONE,
+    0x10: common.Meal.BEFORE,
+    0x20: common.Meal.AFTER,
 }
 
 def parse_reading(msgdata):