Easier and more self documenting patterns for loading/saving Persistent

[python_utils.git] / letter_compress.py

diff --git a/letter_compress.py b/letter_compress.py
index d5a4d60ef06483ee07bd2761e10a5ee9bba7385e..8d7c8d7259d62be5c30d19432e402eedd06bcffa 100644 (file)
--- a/letter_compress.py
+++ b/letter_compress.py
@@ -1,10 +1,14 @@
 #!/usr/bin/env python3
 
+# © Copyright 2021-2022, Scott Gasch
+
+"""A simple toy compression helper for lowercase ascii text."""
+
 import bitstring
 
-from collect.bidict import bidict
+from collect.bidict import BiDict
 
-special_characters = bidict(
+special_characters = BiDict(
     {
         ' ': 27,
         '.': 28,
@@ -32,9 +36,9 @@ def compress(uncompressed: str) -> bytes:
 
     """
     compressed = bitstring.BitArray()
-    for (n, letter) in enumerate(uncompressed):
+    for letter in uncompressed:
         if 'a' <= letter <= 'z':
-            bits = ord(letter) - ord('a') + 1   # 1..26
+            bits = ord(letter) - ord('a') + 1  # 1..26
         else:
             if letter not in special_characters:
                 raise Exception(f'"{uncompressed}" contains uncompressable char="{letter}"')
@@ -70,12 +74,12 @@ def decompress(kompressed: bytes) -> str:
     # complete the partial 4th byte.  In the 4th byte, however, one
     # bit is information and seven are padding.
     #
-    # It's likely that this APIs client code will treat a zero byte as
-    # a termination character and not regard it as part of the
-    # message.  This is a bug in the client code.
+    # It's likely that this API's client code may treat a zero byte as
+    # a termination character and not regard it as a legitimate part
+    # of the message.  This is a bug in that client code, to be clear.
     #
     # However, it's a bug we can work around:
-
+    #
     # Here, I'm appending an extra 0x00 byte to the compressed message
     # passed in.  If the client code dropped the last 0x00 byte (and,
     # with it, some of the legitimate message bits) by treating it as
@@ -100,4 +104,5 @@ def decompress(kompressed: bytes) -> str:
 
 if __name__ == '__main__':
     import doctest
+
     doctest.testmod()