Performance improvements

Changelog.rst

@@ -133,7 +133,7 @@ version 3.5.0
 
 * Changed the API to `cf.Field.period`: Now sets and reports on the
   period of the field construct data, rather than that of its metadata
-  constucts.
+  constructs.
 * Enabled configuration of the extent and nature of informational and
   warning messages output by `cf` using a logging framework (see
   points below and also https://github.com/NCAS-CMS/cf-python/issues/37)

cf/__init__.py

@@ -220,6 +220,7 @@
 from .timeduration import TimeDuration, Y, M, D, h, m, s
 from .units import Units
 
+from .constructlist import ConstructList
 from .fieldlist import FieldList
 
 from .dimensioncoordinate import DimensionCoordinate
@@ -283,7 +284,7 @@
 from .constants import *  # noqa: F403
 from .functions import *  # noqa: F403
 from .maths import relative_vorticity, histogram
-from .examplefield import example_field
+from .examplefield import example_field, example_fields, example_domain
 
 
 from .cfimplementation import CFImplementation, implementation