Replaced _CubeFilterCollection.merged() with combined(); replace uses in load;load_cube/load_cubes.

Author: pp-mo

lib/iris/__init__.py

@@ -405,15 +405,15 @@ def _current_effective_policy():
     return policy
 
 
-def _apply_loading_policy(cubes, policy=None):
+def _combine_with_loading_policy(cubes, policy=None, merge_require_unique=False):
     if not policy:
         policy = _current_effective_policy()
     while True:
         n_original_cubes = len(cubes)
         if policy.use_concatenate and policy.cat_before_merge:
             cubes = cubes.concatenate()
         if policy.use_merge:
-            cubes = cubes.merge()
+            cubes = cubes.merge(unique=merge_require_unique)
         if policy.use_concatenate and not policy.cat_before_merge:
             cubes = cubes.concatenate()
         n_new_cubes = len(cubes)
@@ -447,8 +447,7 @@ def load(uris, constraints=None, callback=None, policy=None):
         were random.
 
     """
-    cubes = _load_collection(uris, constraints, callback).cubes()
-    cubes = _apply_loading_policy(cubes)
+    cubes = _load_collection(uris, constraints, callback).combined().cubes()
     return cubes
 
 
@@ -477,9 +476,11 @@ def load_cube(uris, constraint=None, callback=None):
     if len(constraints) != 1:
         raise ValueError("only a single constraint is allowed")
 
-    cubes = _load_collection(uris, constraints, callback).cubes()
+    cubes = _load_collection(uris, constraints, callback).combined(unique=False)
 
     try:
+        # NOTE: this call currently retained to preserve the legacy exceptions
+        # TODO: replace with simple testing to duplicate the relevant error cases
         cube = cubes.merge_cube()
     except iris.exceptions.MergeError as e:
         raise iris.exceptions.ConstraintMismatchError(str(e))
@@ -514,7 +515,7 @@ def load_cubes(uris, constraints=None, callback=None):
 
     """
     # Merge the incoming cubes
-    collection = _load_collection(uris, constraints, callback).merged()
+    collection = _load_collection(uris, constraints, callback).combined()
 
     # Make sure we have exactly one merged cube per constraint
     bad_pairs = [pair for pair in collection.pairs if len(pair) != 1]

lib/iris/cube.py

@@ -64,6 +64,8 @@ class _CubeFilter:
     """A constraint, paired with a list of cubes matching that constraint."""
 
     def __init__(self, constraint, cubes=None):
+        from iris.cube import CubeList
+
         self.constraint = constraint
         if cubes is None:
             cubes = CubeList()
@@ -78,7 +80,7 @@ def add(self, cube):
         if sub_cube is not None:
             self.cubes.append(sub_cube)
 
-    def merged(self, unique=False):
+    def combined(self, unique=False):
         """Return a new :class:`_CubeFilter` by merging the list of cubes.
 
         Parameters
@@ -88,7 +90,12 @@ def merged(self, unique=False):
             duplicate cubes are detected.
 
         """
-        return _CubeFilter(self.constraint, self.cubes.merge(unique))
+        from iris import _combine_with_loading_policy
+
+        return _CubeFilter(
+            self.constraint,
+            _combine_with_loading_policy(self.cubes, merge_require_unique=unique),
+        )
 
 
 class _CubeFilterCollection:
@@ -114,12 +121,14 @@ def add_cube(self, cube):
 
     def cubes(self):
         """Return all the cubes in this collection in a single :class:`CubeList`."""
+        from iris.cube import CubeList
+
         result = CubeList()
         for pair in self.pairs:
             result.extend(pair.cubes)
         return result
 
-    def merged(self, unique=False):
+    def combined(self, unique=False):
         """Return a new :class:`_CubeFilterCollection` by merging all the cube lists of this collection.
 
         Parameters
@@ -129,7 +138,7 @@ def merged(self, unique=False):
             duplicate cubes are detected.
 
         """
-        return _CubeFilterCollection([pair.merged(unique) for pair in self.pairs])
+        return _CubeFilterCollection([pair.combined(unique) for pair in self.pairs])
 
 
 class CubeList(list):