crc32c as optional dep

Author: normanrz

.github/workflows/ci.yaml

@@ -61,7 +61,7 @@ jobs:
           conda activate env
           export DISABLE_NUMCODECS_AVX2=""
           # TODO: put back zfpy import when it supports numpy 2.0
-          python -m pip install -v -e .[test,test_extras,msgpack]
+          python -m pip install -v -e .[test,test_extras,msgpack,crc32c]
 
       - name: Install pcodec
         if: matrix.python-version != '3.13.0'

numcodecs/checksum32.py

@@ -3,7 +3,6 @@
 from typing import Literal
 
 import numpy as np
-from crc32c import crc32c as crc32c_
 
 from .abc import Codec
 from .compat import ensure_contiguous_ndarray, ndarray_copy
@@ -83,7 +82,15 @@ class CRC32C(Checksum32):
     """
 
     codec_id = 'crc32c'
-    checksum = crc32c_
+
+    def checksum(self, buf):
+        try:
+            from crc32c import crc32c as crc32c_
+
+            return crc32c_(buf)
+        except ImportError:
+            raise ImportError("crc32c must be installed to use the CRC32C checksum codec.")
+
     location = 'end'
 
 

pyproject.toml

@@ -16,7 +16,6 @@ for use in data storage and communication applications."""
 readme =  "README.rst"
 dependencies = [
     "numpy>=1.7",
-    "crc32c>=2.7",
 ]
 requires-python = ">=3.10"
 dynamic = [
@@ -71,6 +70,9 @@ zfpy = [
 pcodec = [
     "pcodec>=0.2.0",
 ]
+crc32c = [
+    "crc32c>=2.7",
+]
 
 [tool.setuptools]
 license-files = ["LICENSE.txt"]