Add the UnknownCodecError

Author: cwognum

numcodecs/errors.py

@@ -0,0 +1,17 @@
+"""
+This module defines custom exceptions that are raised in the `numcodecs` codebase.
+"""
+
+class UnknownCodecError(Exception):
+    """
+    An exception that is raised when trying to receive a codec that has not been registered.
+    
+    Parameters
+    ----------
+    codec_id : str
+        Codec identifier.
+    """
+
+    def __init__(self, codec_id: str):
+        self.codec_id = codec_id
+        super().__init__(f"codec not available: '{codec_id}'")

numcodecs/registry.py

@@ -5,6 +5,7 @@
 from importlib.metadata import EntryPoints, entry_points
 
 from numcodecs.abc import Codec
+from numcodecs.errors import UnknownCodecError
 
 logger = logging.getLogger("numcodecs")
 codec_registry: dict[str, Codec] = {}
@@ -50,7 +51,7 @@ def get_codec(config):
         register_codec(cls, codec_id=codec_id)
     if cls:
         return cls.from_config(config)
-    raise ValueError(f'codec not available: {codec_id!r}')
+    raise UnknownCodecError(f"{codec_id!r}")
 
 
 def register_codec(cls, codec_id=None):