Separate netcdf load and save

lib/iris/experimental/ugrid/__init__.py

@@ -39,8 +39,9 @@
 from ...config import get_logger
 from ...coords import AuxCoord, _DimensionalMetadata
 from ...exceptions import ConnectivityNotFoundError, CoordinateNotFoundError
-from ...fileformats import cf, netcdf
+from ...fileformats import cf
 from ...fileformats._nc_load_rules.helpers import get_attr_units, get_names
+from ...fileformats.netcdf import loader as nc_loader
 from ...io import decode_uri, expand_filespecs
 from ...util import guess_coord_axis
 
@@ -3359,7 +3360,7 @@ def load_meshes(uris, var_name=None):
     from iris.fileformats import FORMAT_AGENT
 
     if not PARSE_UGRID_ON_LOAD:
-        # Explicit behaviour, consistent with netcdf.load_cubes(), rather than
+        # Explicit behaviour, consistent with netcdf.loader.load_cubes(), rather than
         #  an invisible assumption.
         message = (
             f"PARSE_UGRID_ON_LOAD is {bool(PARSE_UGRID_ON_LOAD)}. Must be "
@@ -3395,7 +3396,7 @@ def load_meshes(uris, var_name=None):
             else:
                 handling_format_spec = FORMAT_AGENT.get_spec(source, None)
 
-            if handling_format_spec.handler == netcdf.load_cubes:
+            if handling_format_spec.handler == nc_loader.load_cubes:
                 valid_sources.append(source)
             else:
                 message = f"Ignoring non-NetCDF file: {source}"
@@ -3718,7 +3719,7 @@ class CFUGridReader(cf.CFReader):
 
 ############
 # Object construction.
-# Helper functions, supporting netcdf.load_cubes ONLY, expected to
+# Helper functions, supporting netcdf.loader.load_cubes ONLY, expected to
 # altered/moved when pyke is removed.
 
 
@@ -3733,7 +3734,7 @@ def _build_aux_coord(coord_var, file_path):
     assert isinstance(coord_var, CFUGridAuxiliaryCoordinateVariable)
     attributes = {}
     attr_units = get_attr_units(coord_var, attributes)
-    points_data = netcdf._get_cf_var_data(coord_var, file_path)
+    points_data = nc_loader._get_cf_var_data(coord_var, file_path)
 
     # Bounds will not be loaded:
     # Bounds may be present, but the UGRID conventions state this would
@@ -3785,7 +3786,7 @@ def _build_connectivity(connectivity_var, file_path, location_dims):
     assert isinstance(connectivity_var, CFUGridConnectivityVariable)
     attributes = {}
     attr_units = get_attr_units(connectivity_var, attributes)
-    indices_data = netcdf._get_cf_var_data(connectivity_var, file_path)
+    indices_data = nc_loader._get_cf_var_data(connectivity_var, file_path)
 
     cf_role = connectivity_var.cf_role
     start_index = connectivity_var.start_index
@@ -3952,7 +3953,7 @@ def _build_mesh(cf, mesh_var, file_path):
     )
     mesh_elements = filter(None, mesh_elements)
     for iris_object in mesh_elements:
-        netcdf._add_unused_attributes(
+        nc_loader._add_unused_attributes(
             iris_object, cf.cf_group[iris_object.var_name]
         )
 

lib/iris/fileformats/__init__.py

@@ -90,7 +90,11 @@ def _load_grib(*args, **kwargs):
 #
 FORMAT_AGENT.add_spec(
     FormatSpecification(
-        "NetCDF", MagicNumber(4), 0x43444601, netcdf.load_cubes, priority=5
+        "NetCDF",
+        MagicNumber(4),
+        0x43444601,
+        netcdf.loader.load_cubes,
+        priority=5,
     )
 )
 
@@ -100,7 +104,7 @@ def _load_grib(*args, **kwargs):
         "NetCDF 64 bit offset format",
         MagicNumber(4),
         0x43444602,
-        netcdf.load_cubes,
+        netcdf.loader.load_cubes,
         priority=5,
     )
 )
@@ -112,7 +116,7 @@ def _load_grib(*args, **kwargs):
         "NetCDF_v4",
         MagicNumber(8),
         0x894844460D0A1A0A,
-        netcdf.load_cubes,
+        netcdf.loader.load_cubes,
         priority=5,
     )
 )
@@ -122,7 +126,7 @@ def _load_grib(*args, **kwargs):
     "NetCDF OPeNDAP",
     UriProtocol(),
     lambda protocol: protocol in ["http", "https"],
-    netcdf.load_cubes,
+    netcdf.loader.load_cubes,
     priority=6,
 )
 FORMAT_AGENT.add_spec(_nc_dap)

lib/iris/fileformats/_nc_load_rules/engine.py

@@ -5,7 +5,7 @@
 # licensing details.
 """
 A simple mimic of the Pyke 'knowledge_engine', for interfacing to the routines
-in 'iris.fileformats.netcdf' with minimal changes to that code.
+in 'iris.fileformats.netcdf.loader' with minimal changes to that code.
 
 This allows us to replace the Pyke rules operation with the simpler pure-Python
 translation operations in :mod:`iris.fileformats._nc_load_rules.actions`.
@@ -15,7 +15,7 @@
 
 engine.get_kb() also returns a FactEntity object, which mimics *just enough*
 API of a Pyke.knowlege_base, so that we can list its case-specific facts, as
-used in :meth:`iris.fileformats.netcdf._actions_activation_stats`.
+used in :meth:`iris.fileformats.netcdf.loader._actions_activation_stats`.
 
 """
 from .actions import run_actions
@@ -66,7 +66,7 @@ class Engine:
     A minimal mimic of a Pyke.engine.
 
     Provides just enough API so that the existing code in
-    :mod:`iris.fileformats.netcdf` can interface with our new rules functions.
+    :mod:`iris.fileformats.netcdf.loader` can interface with our new rules functions.
 
     A list of possible fact-arglists is stored, for each of a set of fact-names
     (which are strings).
@@ -91,7 +91,7 @@ def activate(self):
         set by engine.cf_var (a CFDataVariable).
 
         The rules operation itself is coded elsewhere,
-        in :mod:`iris.fileformats.netcdf._nc_load_rules.actions`.
+        in :mod:`iris.fileformats.netcdf.loader._nc_load_rules.actions`.
 
         """
         run_actions(self)
@@ -101,7 +101,7 @@ def get_kb(self):
         Get a FactEntity, which mimic (bits of) a knowledge-base.
 
         Just allowing
-        :meth:`iris.fileformats.netcdf._action_activation_stats` to list the
+        :meth:`iris.fileformats.netcdf.loader._action_activation_stats` to list the
         facts.
 
         """
@@ -110,7 +110,7 @@ def get_kb(self):
     def print_stats(self):
         """
         No-op, called by
-        :meth:`iris.fileformats.netcdf._action_activation_stats`.
+        :meth:`iris.fileformats.netcdf.loader._action_activation_stats`.
 
         """
         pass

lib/iris/fileformats/_nc_load_rules/helpers.py

@@ -26,8 +26,7 @@
 import iris.coords
 import iris.exceptions
 import iris.fileformats.cf as cf
-import iris.fileformats.netcdf
-from iris.fileformats.netcdf import (
+from iris.fileformats.netcdf.loader import (
     UnknownCellMethodWarning,
     _get_cf_var_data,
     parse_cell_methods,

lib/iris/fileformats/netcdf/__init__.py

@@ -0,0 +1,28 @@
+# Copyright Iris contributors
+#
+# This file is part of Iris and is released under the LGPL license.
+# See COPYING and COPYING.LESSER in the root of the repository for full
+# licensing details.
+"""
+A package for loading and saving cubes to and from netcdf files.
+
+"""
+from .loader import (
+    NetCDFDataProxy,
+    OrderedAddableList,
+    UnknownCellMethodWarning,
+    load_cubes,
+    parse_cell_methods,
+)
+from .saver import CFNameCoordMap, Saver, save
+
+__all__ = [
+    "CFNameCoordMap",
+    "NetCDFDataProxy",
+    "OrderedAddableList",
+    "Saver",
+    "UnknownCellMethodWarning",
+    "load_cubes",
+    "parse_cell_methods",
+    "save",
+]