allow refreshing of backends

xarray/backends/cfgrib_.py

@@ -9,7 +9,7 @@
     BACKEND_ENTRYPOINTS,
     AbstractDataStore,
     BackendArray,
-    BackendEntrypoint,
+    _InternalBackendEntrypoint,
     _normalize_path,
 )
 from xarray.backends.locks import SerializableLock, ensure_lock
@@ -90,7 +90,8 @@ def get_encoding(self):
         return {"unlimited_dims": {k for k, v in dims.items() if v is None}}
 
 
-class CfgribfBackendEntrypoint(BackendEntrypoint):
+class CfgribfBackendEntrypoint(_InternalBackendEntrypoint):
+    _module_name = "cfgrib"
     available = module_available("cfgrib")
 
     def guess_can_open(self, filename_or_obj):

xarray/backends/common.py

@@ -12,7 +12,12 @@
 from xarray.conventions import cf_encoder
 from xarray.core import indexing
 from xarray.core.pycompat import is_duck_dask_array
-from xarray.core.utils import FrozenDict, NdimSizeLenMixin, is_remote_uri
+from xarray.core.utils import (
+    FrozenDict,
+    NdimSizeLenMixin,
+    is_remote_uri,
+    module_available,
+)
 
 if TYPE_CHECKING:
     from io import BufferedIOBase
@@ -428,4 +433,24 @@ def guess_can_open(
         return False
 
 
-BACKEND_ENTRYPOINTS: dict[str, type[BackendEntrypoint]] = {}
+class _InternalBackendEntrypoint:
+    """
+    Wrapper class for BackendEntrypoints that ship with xarray.
+
+
+    Additional attributes
+    ----------
+
+    _module_name : str
+        Name of the module that is required to enable the backend.
+    """
+
+    _module_name: ClassVar[str]
+
+    @classmethod
+    def _set_availability(cls) -> None:
+        """Resets the backends availability."""
+        cls.available = module_available(cls._module_name)
+
+
+BACKEND_ENTRYPOINTS: dict[str, type[_InternalBackendEntrypoint]] = {}

xarray/backends/h5netcdf_.py

@@ -8,8 +8,8 @@
 
 from xarray.backends.common import (
     BACKEND_ENTRYPOINTS,
-    BackendEntrypoint,
     WritableCFDataStore,
+    _InternalBackendEntrypoint,
     _normalize_path,
     find_root_and_group,
 )
@@ -343,7 +343,7 @@ def close(self, **kwargs):
         self._manager.close(**kwargs)
 
 
-class H5netcdfBackendEntrypoint(BackendEntrypoint):
+class H5netcdfBackendEntrypoint(_InternalBackendEntrypoint):
     """
     Backend for netCDF files based on the h5netcdf package.
 
@@ -365,6 +365,7 @@ class H5netcdfBackendEntrypoint(BackendEntrypoint):
     backends.ScipyBackendEntrypoint
     """
 
+    _module_name = "h5netcdf"
     available = module_available("h5netcdf")
     description = (
         "Open netCDF (.nc, .nc4 and .cdf) and most HDF5 files using h5netcdf in Xarray"

xarray/backends/netCDF4_.py

@@ -11,8 +11,8 @@
 from xarray.backends.common import (
     BACKEND_ENTRYPOINTS,
     BackendArray,
-    BackendEntrypoint,
     WritableCFDataStore,
+    _InternalBackendEntrypoint,
     _normalize_path,
     find_root_and_group,
     robust_getitem,
@@ -513,7 +513,7 @@ def close(self, **kwargs):
         self._manager.close(**kwargs)
 
 
-class NetCDF4BackendEntrypoint(BackendEntrypoint):
+class NetCDF4BackendEntrypoint(_InternalBackendEntrypoint):
     """
     Backend for netCDF files based on the netCDF4 package.
 
@@ -535,6 +535,7 @@ class NetCDF4BackendEntrypoint(BackendEntrypoint):
     backends.ScipyBackendEntrypoint
     """
 
+    _module_name = "netCDF4"
     available = module_available("netCDF4")
     description = (
         "Open netCDF (.nc, .nc4 and .cdf) and most HDF5 files using netCDF4 in Xarray"

xarray/backends/plugins.py

@@ -6,20 +6,21 @@
 import sys
 import warnings
 from importlib.metadata import entry_points
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, Callable
 
 from xarray.backends.common import BACKEND_ENTRYPOINTS, BackendEntrypoint
 
 if TYPE_CHECKING:
     import os
+    from importlib.metadata import EntryPoint, EntryPoints
     from io import BufferedIOBase
 
     from xarray.backends.common import AbstractDataStore
 
 STANDARD_BACKENDS_ORDER = ["netcdf4", "h5netcdf", "scipy"]
 
 
-def remove_duplicates(entrypoints):
+def remove_duplicates(entrypoints: EntryPoints) -> list[EntryPoint]:
     # sort and group entrypoints by name
     entrypoints = sorted(entrypoints, key=lambda ep: ep.name)
     entrypoints_grouped = itertools.groupby(entrypoints, key=lambda ep: ep.name)
@@ -42,7 +43,7 @@ def remove_duplicates(entrypoints):
     return unique_entrypoints
 
 
-def detect_parameters(open_dataset):
+def detect_parameters(open_dataset: Callable) -> tuple[str, ...]:
     signature = inspect.signature(open_dataset)
     parameters = signature.parameters
     parameters_list = []
@@ -60,7 +61,9 @@ def detect_parameters(open_dataset):
     return tuple(parameters_list)
 
 
-def backends_dict_from_pkg(entrypoints):
+def backends_dict_from_pkg(
+    entrypoints: list[EntryPoint],
+) -> dict[str, BackendEntrypoint]:
     backend_entrypoints = {}
     for entrypoint in entrypoints:
         name = entrypoint.name
@@ -72,14 +75,16 @@ def backends_dict_from_pkg(entrypoints):
     return backend_entrypoints
 
 
-def set_missing_parameters(backend_entrypoints):
-    for name, backend in backend_entrypoints.items():
+def set_missing_parameters(backend_entrypoints: dict[str, BackendEntrypoint]):
+    for _, backend in backend_entrypoints.items():
         if backend.open_dataset_parameters is None:
             open_dataset = backend.open_dataset
             backend.open_dataset_parameters = detect_parameters(open_dataset)
 
 
-def sort_backends(backend_entrypoints):
+def sort_backends(
+    backend_entrypoints: dict[str, BackendEntrypoint]
+) -> dict[str, BackendEntrypoint]:
     ordered_backends_entrypoints = {}
     for be_name in STANDARD_BACKENDS_ORDER:
         if backend_entrypoints.get(be_name, None) is not None:
@@ -90,7 +95,7 @@ def sort_backends(backend_entrypoints):
     return ordered_backends_entrypoints
 
 
-def build_engines(entrypoints) -> dict[str, BackendEntrypoint]:
+def build_engines(entrypoints: EntryPoints) -> dict[str, BackendEntrypoint]:
     backend_entrypoints = {}
     for backend_name, backend in BACKEND_ENTRYPOINTS.items():
         if backend.available:
@@ -126,6 +131,13 @@ def list_engines() -> dict[str, BackendEntrypoint]:
     return build_engines(entrypoints)
 
 
+def refresh_engines() -> None:
+    """Refreshes the backend engines based on installed packages."""
+    list_engines.cache_clear()
+    for backend_entrypoint in BACKEND_ENTRYPOINTS.values():
+        backend_entrypoint._set_availability()
+
+
 def guess_engine(
     store_spec: str | os.PathLike[Any] | BufferedIOBase | AbstractDataStore,
 ):

xarray/backends/pseudonetcdf_.py

@@ -6,7 +6,7 @@
     BACKEND_ENTRYPOINTS,
     AbstractDataStore,
     BackendArray,
-    BackendEntrypoint,
+    _InternalBackendEntrypoint,
     _normalize_path,
 )
 from xarray.backends.file_manager import CachingFileManager
@@ -96,7 +96,7 @@ def close(self):
         self._manager.close()
 
 
-class PseudoNetCDFBackendEntrypoint(BackendEntrypoint):
+class PseudoNetCDFBackendEntrypoint(_InternalBackendEntrypoint):
     """
     Backend for netCDF-like data formats in the air quality field
     based on the PseudoNetCDF package.
@@ -121,6 +121,7 @@ class PseudoNetCDFBackendEntrypoint(BackendEntrypoint):
     backends.PseudoNetCDFDataStore
     """
 
+    _module_name = "PseudoNetCDF"
     available = module_available("PseudoNetCDF")
     description = (
         "Open many atmospheric science data formats using PseudoNetCDF in Xarray"

xarray/backends/pydap_.py

@@ -7,7 +7,7 @@
     BACKEND_ENTRYPOINTS,
     AbstractDataStore,
     BackendArray,
-    BackendEntrypoint,
+    _InternalBackendEntrypoint,
     robust_getitem,
 )
 from xarray.backends.store import StoreBackendEntrypoint
@@ -138,7 +138,7 @@ def get_dimensions(self):
         return Frozen(self.ds.dimensions)
 
 
-class PydapBackendEntrypoint(BackendEntrypoint):
+class PydapBackendEntrypoint(_InternalBackendEntrypoint):
     """
     Backend for steaming datasets over the internet using
     the Data Access Protocol, also known as DODS or OPeNDAP
@@ -154,6 +154,7 @@ class PydapBackendEntrypoint(BackendEntrypoint):
     backends.PydapDataStore
     """
 
+    _module_name = "pydap"
     available = module_available("pydap")
     description = "Open remote datasets via OPeNDAP using pydap in Xarray"
     url = "https://docs.xarray.dev/en/stable/generated/xarray.backends.PydapBackendEntrypoint.html"

xarray/backends/pynio_.py

@@ -8,7 +8,7 @@
     BACKEND_ENTRYPOINTS,
     AbstractDataStore,
     BackendArray,
-    BackendEntrypoint,
+    _InternalBackendEntrypoint,
     _normalize_path,
 )
 from xarray.backends.file_manager import CachingFileManager
@@ -107,7 +107,7 @@ def close(self):
         self._manager.close()
 
 
-class PynioBackendEntrypoint(BackendEntrypoint):
+class PynioBackendEntrypoint(_InternalBackendEntrypoint):
     """
     PyNIO backend
 
@@ -117,6 +117,7 @@ class PynioBackendEntrypoint(BackendEntrypoint):
         https://github.com/pydata/xarray/issues/4491 for more information
     """
 
+    _module_name = "Nio"
     available = module_available("Nio")
 
     def open_dataset(

xarray/backends/scipy_.py

@@ -9,8 +9,8 @@
 from xarray.backends.common import (
     BACKEND_ENTRYPOINTS,
     BackendArray,
-    BackendEntrypoint,
     WritableCFDataStore,
+    _InternalBackendEntrypoint,
     _normalize_path,
 )
 from xarray.backends.file_manager import CachingFileManager, DummyFileManager
@@ -240,7 +240,7 @@ def close(self):
         self._manager.close()
 
 
-class ScipyBackendEntrypoint(BackendEntrypoint):
+class ScipyBackendEntrypoint(_InternalBackendEntrypoint):
     """
     Backend for netCDF files based on the scipy package.
 
@@ -261,6 +261,7 @@ class ScipyBackendEntrypoint(BackendEntrypoint):
     backends.H5netcdfBackendEntrypoint
     """
 
+    _module_name = "scipy"
     available = module_available("scipy")
     description = "Open netCDF files (.nc, .nc4, .cdf and .gz) using scipy in Xarray"
     url = "https://docs.xarray.dev/en/stable/generated/xarray.backends.ScipyBackendEntrypoint.html"

xarray/backends/zarr.py

@@ -11,8 +11,8 @@
     BACKEND_ENTRYPOINTS,
     AbstractWritableDataStore,
     BackendArray,
-    BackendEntrypoint,
     _encode_variable_name,
+    _InternalBackendEntrypoint,
     _normalize_path,
 )
 from xarray.backends.store import StoreBackendEntrypoint
@@ -845,7 +845,7 @@ def open_zarr(
     return ds
 
 
-class ZarrBackendEntrypoint(BackendEntrypoint):
+class ZarrBackendEntrypoint(_InternalBackendEntrypoint):
     """
     Backend for ".zarr" files based on the zarr package.
 
@@ -857,6 +857,7 @@ class ZarrBackendEntrypoint(BackendEntrypoint):
     backends.ZarrStore
     """
 
+    _module_name = "zarr"
     available = module_available("zarr")
     description = "Open zarr files (.zarr) using zarr in Xarray"
     url = "https://docs.xarray.dev/en/stable/generated/xarray.backends.ZarrBackendEntrypoint.html"