Merge pull request #30 from alaniwi/add_obj_example

add object-oriented example code for the temperature probe

python/exercises/example_code/temperature_probe_object_oriented_example/example_output1.txt

@@ -0,0 +1,6 @@
+$ python main1.py 
+2018-11-23T11:25:41.135225 temperature = 23.3 degrees
+2018-11-23T11:25:51.087159 temperature = 23.1 degrees
+2018-11-23T11:26:01.039236 temperature = 27.4 degrees
+2018-11-23T11:26:10.991217 temperature = 27.3 degrees
+2018-11-23T11:26:20.943257 temperature = 26.4 degrees

python/exercises/example_code/temperature_probe_object_oriented_example/example_output2.txt

@@ -0,0 +1,12 @@
+$ python main2.py 
+2018-11-23T11:26:34.005752 current=25.6 min=25.6 max=25.6
+2018-11-23T11:26:43.955339 current=25.2 min=25.2 max=25.6
+2018-11-23T11:26:53.907398 current=24.7 min=24.7 max=25.6
+2018-11-23T11:27:03.860271 current=24.4 min=24.4 max=25.6
+2018-11-23T11:27:13.812171 current=24.1 min=24.1 max=25.6
+2018-11-23T11:27:23.765222 current=23.9 min=23.9 max=25.6
+Resetting max and min
+2018-11-23T11:27:33.717196 current=28.7 min=28.7 max=28.7
+2018-11-23T11:27:43.669152 current=30.8 min=28.7 max=30.8
+2018-11-23T11:27:53.622132 current=31.7 min=28.7 max=31.7
+2018-11-23T11:28:03.575222 current=30.4 min=28.7 max=31.7

python/exercises/example_code/temperature_probe_object_oriented_example/main1.py

@@ -0,0 +1,10 @@
+from thermometer import Thermometer
+
+thermometer = Thermometer()
+
+for i in range(5):
+    temp, when = thermometer.get_measurement()
+    print("{} temperature = {} degrees".format(when.isoformat(),
+                                               temp))
+
+thermometer.close()

python/exercises/example_code/temperature_probe_object_oriented_example/main2.py

@@ -0,0 +1,17 @@
+from max_min_thermometer import MaxMinThermometer
+
+mmt = MaxMinThermometer()
+
+for i in range(10):
+
+    temp, when = mmt.get_measurement()
+    print("{} current={} min={} max={}".format(when.isoformat(),
+                                               temp,
+                                               mmt.min,
+                                               mmt.max))
+
+    if i == 5:
+        print("Resetting max and min")
+        mmt.reset_max_min()
+
+mmt.close()

python/exercises/example_code/temperature_probe_object_oriented_example/max_min_thermometer.py

@@ -0,0 +1,35 @@
+from thermometer import Thermometer
+
+
+class MaxMinThermometer(object):
+    """
+    a maximum minimum thermometer which encapsulates (i.e. contains) 
+    a thermometer and also stores min / max temperature data
+    """
+
+    def __init__(self):
+        self.thermometer = Thermometer()
+        self.min = None
+        self.max = None
+
+
+    def get_measurement(self):        
+        (temp, when) = self.thermometer.get_measurement()
+        self.update_max_min(temp)
+        return (temp, when)
+
+
+    def update_max_min(self, temp):
+        if self.min == None or self.min > temp:
+            self.min = temp
+        if self.max == None or self.max < temp:
+            self.max = temp
+
+
+    def reset_max_min(self):
+        self.min = None
+        self.max = None
+
+
+    def close(self):
+        self.thermometer.close()

python/exercises/example_code/temperature_probe_object_oriented_example/thermometer.py

@@ -0,0 +1,33 @@
+from datetime import datetime
+import io
+import serial
+
+
+class Thermometer(object):
+
+    def __init__(self):
+        """
+        Initialise the thermometer
+        """
+        self.ser = serial.Serial(
+            port='/dev/ttyUSB0', 
+            baudrate=9600) 
+        self.sio = io.TextIOWrapper(
+            io.BufferedRWPair(self.ser, self.ser, 1),
+            encoding='ascii', newline='\r')
+        self.sio._CHUNK_SIZE = 1
+
+
+    def get_measurement(self):
+        """
+        Returns tuple of (temperature, when)
+        temperature is float and when is datetime object
+        """
+        datastring = self.sio.readline().strip()
+        temp = float(datastring[:6])
+        when = datetime.utcnow()
+        return (temp, when)
+
+
+    def close(self):
+        self.ser.close()