code review updates

Author: caternuson

.pylintrc

@@ -156,7 +156,7 @@ ignored-classes=optparse.Values,thread._local,_thread._local
 # (useful for modules/projects where namespaces are manipulated during runtime
 # and thus existing member attributes cannot be deduced by static analysis. It
 # supports qualified module names, as well as Unix pattern matching.
-ignored-modules=
+ignored-modules=board
 
 # Show a hint with possible names when a member name was not found. The aspect
 # of finding the hint is based on edit distance.

.travis.yml

@@ -23,7 +23,8 @@ deploy:
     tags: true
 
 install:
-  - pip install pylint circuitpython-build-tools Sphinx sphinx-rtd-theme
+  - pip install circuitpython-build-tools Sphinx sphinx-rtd-theme
+  - pip install --force-reinstall pylint==1.9.2
 
 script:
   - pylint adafruit_tca9548a.py

adafruit_tca9548a.py

@@ -89,12 +89,14 @@ class TCA9548A():
     def __init__(self, i2c, address=_DEFAULT_ADDRESS):
         self.i2c = i2c
         self.address = address
-        self.used_channels = []
+        self.channels = [None]*8
+
+    def __len__(self):
+        return 8
 
     def __getitem__(self, key):
         if not 0 <= key <= 7:
-            raise ValueError("Channel must be an integer in the range: 0-7")
-        if key in self.used_channels:
-            raise ValueError("Channel already in use.")
-        self.used_channels.append(key)
-        return TCA9548A_Channel(self, key)
+            raise IndexError("Channel must be an integer in the range: 0-7")
+        if self.channels[key] is None:
+            self.channels[key] = TCA9548A_Channel(self, key)
+        return self.channels[key]

requirements.txt

@@ -1 +0,0 @@
-adafruit-circuitpython-busdevice