[#19] Add type annotations

adafruit_pm25/__init__.py

@@ -50,7 +50,7 @@ class PM25:
 
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
         # rad, ok make our internal buffer!
         self._buffer = bytearray(32)
         self.aqi_reading = {
@@ -68,11 +68,11 @@ def __init__(self):
             "particles 100um": None,
         }
 
-    def _read_into_buffer(self):
+    def _read_into_buffer(self) -> None:
         """Low level buffer filling function, to be overridden"""
         raise NotImplementedError()
 
-    def read(self):
+    def read(self) -> dict:
         """Read any available data from the air quality sensor and
         return a dictionary with available particulate/quality data"""
         self._read_into_buffer()

adafruit_pm25/i2c.py

@@ -35,10 +35,17 @@
 
 # imports
 import time
-from digitalio import Direction
+from digitalio import Direction, DigitalInOut
 from adafruit_bus_device.i2c_device import I2CDevice
 from . import PM25
 
+try:
+    # Used only for typing
+    import typing  # pylint: disable=unused-import
+    from busio import I2C
+except ImportError:
+    pass
+
 
 class PM25_I2C(PM25):
     """
@@ -77,7 +84,9 @@ class PM25_I2C(PM25):
 
     """
 
-    def __init__(self, i2c_bus, reset_pin=None, address=0x12):
+    def __init__(
+        self, i2c_bus: I2C, reset_pin: DigitalInOut = None, address: int = 0x12
+    ) -> None:
         if reset_pin:
             # Reset device
             reset_pin.direction = Direction.OUTPUT
@@ -98,7 +107,7 @@ def __init__(self, i2c_bus, reset_pin=None, address=0x12):
             raise RuntimeError("Unable to find PM2.5 device")
         super().__init__()
 
-    def _read_into_buffer(self):
+    def _read_into_buffer(self) -> None:
         with self.i2c_device as i2c:
             try:
                 i2c.readinto(self._buffer)

adafruit_pm25/uart.py

@@ -30,9 +30,16 @@
 """
 
 import time
-from digitalio import Direction
+from digitalio import Direction, DigitalInOut
 from . import PM25
 
+try:
+    # Used only for typing
+    import typing  # pylint: disable=unused-import
+    from busio import UART
+except ImportError:
+    pass
+
 
 class PM25_UART(PM25):
     """
@@ -73,7 +80,7 @@ class PM25_UART(PM25):
 
     """
 
-    def __init__(self, uart, reset_pin=None):
+    def __init__(self, uart: UART, reset_pin: DigitalInOut = None):
         if reset_pin:
             # Reset device
             reset_pin.direction = Direction.OUTPUT
@@ -86,7 +93,7 @@ def __init__(self, uart, reset_pin=None):
         self._uart = uart
         super().__init__()
 
-    def _read_into_buffer(self):
+    def _read_into_buffer(self) -> None:
         while True:
             b = self._uart.read(1)
             if not b: