Use more specific exception classes so that other exceptions won't get swaUse more specific exception classes so that other exceptions won't get swallowedllawed

Author: bzaczynski

python-bitwise-operators/stegano/__main__.py

@@ -5,8 +5,8 @@
 
 from .bitmap import Bitmap
 from .cli import CommandLineArguments, parse_args
-from .decoder import decode
-from .encoder import encode
+from .decoder import decode, DecodingError
+from .encoder import encode, EncodingError
 from .eraser import erase
 
 
@@ -24,5 +24,5 @@ def main(args: CommandLineArguments) -> None:
 if __name__ == "__main__":
     try:
         main(parse_args())
-    except Exception as ex:  # pylint: disable=W0703
+    except (EncodingError, DecodingError) as ex:
         print(ex)

python-bitwise-operators/stegano/decoder.py

@@ -9,11 +9,15 @@
 from .bitmap import Bitmap
 
 
+class DecodingError(Exception):
+    pass
+
+
 def decode(bitmap: Bitmap) -> None:
     """Extract a secret file from the bitmap."""
 
     if bitmap.reserved_field <= 0:
-        raise ValueError("Secret file not found in the bitmap")
+        raise DecodingError("Secret file not found in the bitmap")
 
     iterator = secret_bytes(bitmap)
 

python-bitwise-operators/stegano/encoder.py

@@ -8,6 +8,10 @@
 from .bitmap import Bitmap
 
 
+class EncodingError(Exception):
+    pass
+
+
 class SecretFile:
     """Convenience class for serializing secret data."""
 
@@ -35,7 +39,7 @@ def encode(bitmap: Bitmap, path: pathlib.Path) -> None:
     file = SecretFile(path)
 
     if file.num_secret_bytes > bitmap.max_bytes:
-        raise ValueError("Not enough pixels to embed a secret file")
+        raise EncodingError("Not enough pixels to embed a secret file")
 
     bitmap.reserved_field = file.size_bytes
     for secret_byte, eight_bytes in zip(file.secret_bytes, bitmap.byte_slices):