Reduce the time taken to import cfdm

Changelog.rst

@@ -1,3 +1,13 @@
+Version NEXTVERSION
+-------------------
+
+**2025-12-??**
+
+* Reduce the time taken to import `cfdm`
+  (https://github.com/NCAS-CMS/cfdm/issues/361)
+
+----
+
 Version 1.12.3.1
 ----------------
 

cfdm/__init__.py

@@ -40,174 +40,12 @@
 import logging
 import sys
 
-from packaging.version import Version
-
 from . import core
 
 __date__ = core.__date__
 __cf_version__ = core.__cf_version__
 __version__ = core.__version__
 
-_requires = core._requires + (
-    "cftime",
-    "netCDF4",
-    "dask",
-    "scipy",
-    "h5netcdf",
-    "zarr",
-    "s3fs",
-    "uritools",
-    "cfunits",
-)
-
-_error0 = f"cfdm requires the modules {', '.join(_requires)}. "
-
-# Check the version of cftime
-try:
-    import cftime
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "1.6.4"
-    if Version(cftime.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad cftime version: cfdm requires cftime>={_minimum_vn}. "
-            f"Got {cftime.__version__} at {cftime.__file__}"
-        )
-
-# Check the version of netCDF4
-try:
-    import netCDF4
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "1.7.2"
-    if Version(netCDF4.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad netCDF4 version: cfdm requires netCDF4>={_minimum_vn}. "
-            f"Got {netCDF4.__version__} at {netCDF4.__file__}"
-        )
-
-# Check the version of h5netcdf
-try:
-    import h5netcdf
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "1.3.0"
-    if Version(h5netcdf.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad h5netcdf version: cfdm requires h5netcdf>={_minimum_vn}. "
-            f"Got {h5netcdf.__version__} at {h5netcdf.__file__}"
-        )
-
-# Check the version of h5py
-try:
-    import h5py
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "3.12.0"
-    if Version(h5py.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad h5py version: cfdm requires h5py>={_minimum_vn}. "
-            f"Got {h5py.__version__} at {h5py.__file__}"
-        )
-
-# Check the version of zarr
-try:
-    import zarr
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "3.0.8"
-    if Version(zarr.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad zarr version: cfdm requires zarr>={_minimum_vn}. "
-            f"Got {zarr.__version__} at {zarr.__file__}"
-        )
-
-# Check the version of s3fs
-try:
-    import s3fs
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "2024.6.0"
-    if Version(s3fs.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad s3fs version: cfdm requires s3fs>={_minimum_vn}. "
-            f"Got {s3fs.__version__} at {s3fs.__file__}"
-        )
-
-# Check the version of scipy
-try:
-    import scipy
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "1.10.0"
-    if Version(scipy.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad scipy version: cfdm requires scipy>={_minimum_vn}. "
-            f"Got {scipy.__version__} at {scipy.__file__}"
-        )
-
-# Check the version of dask
-try:
-    import dask
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "2025.5.1"
-    if Version(dask.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad dask version: cfdm requires dask>={_minimum_vn}. "
-            f"Got {dask.__version__} at {dask.__file__}"
-        )
-
-# Check the version of distributed
-try:
-    import distributed
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "2025.5.1"
-    if Version(distributed.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            "Bad distributed version: cfdm requires "
-            f"distributed>={_minimum_vn}. "
-            f"Got {distributed.__version__} at {distributed.__file__}"
-        )
-
-# Check the version of uritools
-try:
-    import uritools
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "4.0.3"
-    if Version(uritools.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad uritools version: cfdm requires uritools>={_minimum_vn}. "
-            f"Got {uritools.__version__} at {uritools.__file__}"
-        )
-
-# Check the version of cfunits
-try:
-    import cfunits
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "3.3.7"
-    if Version(cfunits.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad cfunits version: cfdm requires cfunits>={_minimum_vn}. "
-            f"Got {cfunits.__version__} at {cfunits.__file__}"
-        )
-
-del _minimum_vn
-
 from .constants import masked
 
 # Internal ones passed on so they can be used in cf-python (see

cfdm/constants.py

@@ -1,42 +1,6 @@
-import logging
-import sys
 from enum import Enum
 
 import numpy as np
-from dask import config
-from dask.utils import parse_bytes
-
-_CHUNKSIZE = "128 MiB"
-config.set({"array.chunk-size": _CHUNKSIZE})
-"""A dictionary of useful constants.
-
-Whilst the dictionary may be modified directly, it is safer to
-retrieve and set the values with the dedicated get-and-set functions.
-
-:Keys:
-
-    ATOL: `float`
-      The value of absolute tolerance for testing numerically tolerant
-      equality.
-
-    RTOL: `float`
-      The value of relative tolerance for testing numerically tolerant
-      equality.
-
-    LOG_LEVEL: `str`
-      The minimal level of seriousness for which log messages are
-      shown.  See `cfdm.log_level`.
-
-    CHUNKSIZE: `int`
-      The Dask chunk size (in bytes). See `cfdm.chunksize`.
-
-"""
-CONSTANTS = {
-    "ATOL": sys.float_info.epsilon,
-    "RTOL": sys.float_info.epsilon,
-    "LOG_LEVEL": logging.getLevelName(logging.getLogger().level),
-    "CHUNKSIZE": parse_bytes(_CHUNKSIZE),
-}
 
 
 # --------------------------------------------------------------------

cfdm/constructs.py

@@ -2,14 +2,15 @@
 from itertools import zip_longest
 from re import Pattern
 
-from . import core, mixin
+from .core import Constructs as core_Constructs
 from .core.functions import deepcopy
 from .decorators import _manage_log_level_via_verbosity
+from .mixin import Container
 
 logger = logging.getLogger(__name__)
 
 
-class Constructs(mixin.Container, core.Constructs):
+class Constructs(Container, core_Constructs):
     """A container for metadata constructs.
 
     The container has similarities to a `dict` in that it presents the

cfdm/core/__init__.py

@@ -15,52 +15,12 @@
 __cf_version__ = "1.12"
 __version__ = "1.12.3.1"
 
-from platform import python_version
-
-_requires = ("numpy", "packaging")
-_error0 = f"cfdm.core requires the modules {', '.join(_requires)}. "
-
-# Check the version of packaging
-try:
-    import packaging
-    from packaging.version import Version
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "20.0"
-    if Version(packaging.__version__) < Version(_minimum_vn):
-        raise RuntimeError(
-            f"Bad packaging version: cf requires packaging>={_minimum_vn}. "
-            f"Got {packaging.__version__} at {packaging.__file__}"
-        )
-
-# Check the version of python
-_minimum_vn = "3.10.0"
-if Version(python_version()) < Version(_minimum_vn):
-    raise ValueError(
-        f"Bad python version: cfdm.core requires python>={_minimum_vn}. "
-        f"Got {python_version()}"
-    )
-
-# Check the version of numpy
-try:
-    import numpy as np
-except ImportError as error1:
-    raise ImportError(_error0 + str(error1))
-else:
-    _minimum_vn = "2.0.0"
-    if Version(np.__version__) < Version(_minimum_vn):
-        raise ValueError(
-            f"Bad numpy version: cfdm.core requires numpy>={_minimum_vn}. "
-            f"Got {np.__version__} at {np.__file__}"
-        )
-
-del _minimum_vn
+# Count the number of docstrings (first element), and the number which
+# have docstring substitutions applied to them (second element).
+_docstring_substitutions = [0, 0]
 
 from .constructs import Constructs
-
 from .functions import CF, environment
-
 from .data import Data, Array, NumpyArray
 
 from .bounds import Bounds

cfdm/core/cellconnectivity.py

@@ -105,7 +105,7 @@ def construct_type(self):
     def del_connectivity(self, default=ValueError()):
         """Remove the connectivity.
 
-        {{{cell connectivity type}}
+        {{cell connectivity type}}
 
         .. versionadded:: (cfdm) 1.11.0.0
 
@@ -149,7 +149,7 @@ def del_connectivity(self, default=ValueError()):
     def has_connectivity(self):
         """Whether the connectivity type has been set.
 
-        {{{cell connectivity type}}
+        {{cell connectivity type}}
 
         .. versionadded:: (cfdm) 1.11.0.0
 
@@ -233,7 +233,7 @@ def get_connectivity(self, default=ValueError()):
     def set_connectivity(self, connectivity):
         """Set the connectivity type.
 
-        {{{cell connectivity type}}
+        {{cell connectivity type}}
 
         .. versionadded:: (cfdm) 1.11.0.0
 

cfdm/core/data/abstract/array.py

@@ -1,8 +1,8 @@
 from functools import reduce
 from operator import mul
 
-from ...abstract import Container
-from ...utils import cached_property
+from cfdm.core.abstract import Container
+from cfdm.core.utils import cached_property
 
 
 class Array(Container):

cfdm/core/data/data.py

@@ -1,6 +1,7 @@
 import numpy as np
 
-from .. import abstract
+from cfdm.core import abstract
+
 from .abstract import Array
 from .numpyarray import NumpyArray
 

cfdm/core/docstring/docstring.py

@@ -9,13 +9,7 @@
 
 Replacement text may not contain other non-special substitutions.
 
-Keys must be a `str` or `re.Pattern` object:
-
-* If a key is a `str` then the corresponding value must be a string.
-
-* If a key is a `re.Pattern` object then the corresponding value must
-  be a string or a callable, as accepted by the `re.Pattern.sub`
-  method.
+A key and its corresponding value must both be `str`.
 
 .. versionaddedd:: (cfdm) 1.8.7.0
 
@@ -95,7 +89,10 @@
     "{{init data: data_like, optional}}": """data: data_like, optional
                 Set the data.
 
-                {{data_like}}
+                A data_like object is any object that can be converted
+                to a `Data` object, i.e. `numpy` array_like objects,
+                `Data` objects, and {{package}} instances that contain
+                `Data` objects.
 
                 The data also may be set after initialisation with the
                 `set_data` method.""",