Error at runtime if zfpy isn't present

Author: dstansby

numcodecs/__init__.py

@@ -125,10 +125,9 @@
 register_codec(Fletcher32)
 
 # Optional depenedencies
-with suppress(ImportError):
-    from numcodecs.zfpy import ZFPY
+from numcodecs.zfpy import ZFPY
 
-    register_codec(ZFPY)
+register_codec(ZFPY)
 
 with suppress(ImportError):
     from numcodecs.msgpacks import MsgPack

numcodecs/zfpy.py

@@ -1,113 +1,113 @@
-import warnings
-from contextlib import suppress
-from importlib.metadata import PackageNotFoundError, version
+import importlib.util
+from importlib.metadata import version
 from types import ModuleType
 from typing import Optional
 
-_zfpy: Optional[ModuleType] = None
+import numpy as np
 
-_zfpy_version: tuple = ()
-with suppress(PackageNotFoundError):
-    _zfpy_version = tuple(map(int, version("zfpy").split(".")))
+from .abc import Codec
+from .compat import ensure_bytes, ensure_contiguous_ndarray, ndarray_copy
+
+_zfpy: Optional[ModuleType]
+_zfpy_spec = importlib.util.find_spec("zfpy")
+
+if _zfpy_spec is None:
+    _zfpy = None
+else:
+    import zfpy as _zfpy  # type: ignore[no-redef]
 
-if _zfpy_version:
-    # Check NumPy version
-    _numpy_version: tuple = tuple(map(int, version("numpy").split('.')))
+
+def _check_compatible_numpy() -> None:
+    _numpy_version = tuple(map(int, version("numpy").split('.')))
+    _zfpy_version = tuple(map(int, version("zfpy").split(".")))
     if _numpy_version >= (2, 0, 0) and _zfpy_version <= (1, 0, 1):  # pragma: no cover
         _zfpy_version = ()
-        warnings.warn(
+        raise RuntimeError(
             "NumPy version >= 2.0.0 detected. The zfpy library is incompatible with this version of NumPy. "
             "Please downgrade to NumPy < 2.0.0 or wait for an update from zfpy.",
-            UserWarning,
-            stacklevel=2,
         )
-    else:
-        with suppress(ImportError):
-            import zfpy as _zfpy  # type: ignore[no-redef]
-
-if _zfpy:
-    import numpy as np
-
-    from .abc import Codec
-    from .compat import ensure_bytes, ensure_contiguous_ndarray, ndarray_copy
-
-    # noinspection PyShadowingBuiltins
-    class ZFPY(Codec):
-        """Codec providing compression using zfpy via the Python standard
-        library.
-
-        Parameters
-        ----------
-        mode : integer
-            One of the zfpy mode choice, e.g., ``zfpy.mode_fixed_accuracy``.
-        tolerance : double, optional
-            A double-precision number, specifying the compression accuracy needed.
-        rate : double, optional
-            A double-precision number, specifying the compression rate needed.
-        precision : int, optional
-            A integer number, specifying the compression precision needed.
-
-        """
-
-        codec_id = "zfpy"
-
-        def __init__(
-            self,
-            mode=_zfpy.mode_fixed_accuracy,
-            tolerance=-1,
-            rate=-1,
-            precision=-1,
-            compression_kwargs=None,
-        ):
-            self.mode = mode
-            if mode == _zfpy.mode_fixed_accuracy:
-                self.compression_kwargs = {"tolerance": tolerance}
-            elif mode == _zfpy.mode_fixed_rate:
-                self.compression_kwargs = {"rate": rate}
-            elif mode == _zfpy.mode_fixed_precision:
-                self.compression_kwargs = {"precision": precision}
-
-            self.tolerance = tolerance
-            self.rate = rate
-            self.precision = precision
-
-        def encode(self, buf):
-            # not flatten c-order array and raise exception for f-order array
-            if not isinstance(buf, np.ndarray):
-                raise TypeError(
-                    "The zfp codec does not support none numpy arrays."
-                    f" Your buffers were {type(buf)}."
-                )
-            if buf.flags.c_contiguous:
-                flatten = False
-            else:
-                raise ValueError(
-                    "The zfp codec does not support F order arrays. "
-                    f"Your arrays flags were {buf.flags}."
-                )
-            buf = ensure_contiguous_ndarray(buf, flatten=flatten)
-
-            # do compression
-            return _zfpy.compress_numpy(buf, write_header=True, **self.compression_kwargs)
-
-        def decode(self, buf, out=None):
-            # normalise inputs
-            buf = ensure_bytes(buf)
-            if out is not None:
-                out = ensure_contiguous_ndarray(out)
-
-            # do decompression
-            dec = _zfpy.decompress_numpy(buf)
-
-            # handle destination
-            if out is not None:
-                return ndarray_copy(dec, out)
-            else:
-                return dec
-
-        def __repr__(self):
-            return (
-                f"{type(self).__name__}(mode={self.mode!r}, "
-                f"tolerance={self.tolerance}, rate={self.rate}, "
-                f"precision={self.precision})"
+
+
+class ZFPY(Codec):
+    """Codec providing compression using zfpy via the Python standard
+    library.
+
+    Parameters
+    ----------
+    mode : integer
+        One of the zfpy mode choice, e.g., ``zfpy.mode_fixed_accuracy``.
+    tolerance : double, optional
+        A double-precision number, specifying the compression accuracy needed.
+    rate : double, optional
+        A double-precision number, specifying the compression rate needed.
+    precision : int, optional
+        A integer number, specifying the compression precision needed.
+
+    """
+
+    codec_id = "zfpy"
+
+    def __init__(
+        self,
+        mode=_zfpy.mode_fixed_accuracy,
+        tolerance=-1,
+        rate=-1,
+        precision=-1,
+        compression_kwargs=None,
+    ):
+        if _zfpy is None:
+            raise RuntimeError("The ZFPY codec requires the 'zfpy' package to be installed.")
+        _check_compatible_numpy()
+
+        self.mode = mode
+        if mode == _zfpy.mode_fixed_accuracy:
+            self.compression_kwargs = {"tolerance": tolerance}
+        elif mode == _zfpy.mode_fixed_rate:
+            self.compression_kwargs = {"rate": rate}
+        elif mode == _zfpy.mode_fixed_precision:
+            self.compression_kwargs = {"precision": precision}
+
+        self.tolerance = tolerance
+        self.rate = rate
+        self.precision = precision
+
+    def encode(self, buf):
+        # not flatten c-order array and raise exception for f-order array
+        if not isinstance(buf, np.ndarray):
+            raise TypeError(
+                "The zfp codec does not support none numpy arrays."
+                f" Your buffers were {type(buf)}."
             )
+        if buf.flags.c_contiguous:
+            flatten = False
+        else:
+            raise ValueError(
+                "The zfp codec does not support F order arrays. "
+                f"Your arrays flags were {buf.flags}."
+            )
+        buf = ensure_contiguous_ndarray(buf, flatten=flatten)
+
+        # do compression
+        return _zfpy.compress_numpy(buf, write_header=True, **self.compression_kwargs)
+
+    def decode(self, buf, out=None):
+        # normalise inputs
+        buf = ensure_bytes(buf)
+        if out is not None:
+            out = ensure_contiguous_ndarray(out)
+
+        # do decompression
+        dec = _zfpy.decompress_numpy(buf)
+
+        # handle destination
+        if out is not None:
+            return ndarray_copy(dec, out)
+        else:
+            return dec
+
+    def __repr__(self):
+        return (
+            f"{type(self).__name__}(mode={self.mode!r}, "
+            f"tolerance={self.tolerance}, rate={self.rate}, "
+            f"precision={self.precision})"
+        )