Fix deepcopy bug in CRS

.github/workflows/ci-testing.yml

@@ -33,7 +33,7 @@ jobs:
         if: matrix.python-version == '3.9' && matrix.os == 'ubuntu-latest'
         id: minimum-packages
         run: |
-          pip install cython==0.29.24 matplotlib==3.5.3 numpy==1.21 owslib==0.24.1 pyproj==3.1 scipy==1.6.3 shapely==1.7.1 pyshp==2.3.1
+          pip install cython==0.29.24 matplotlib==3.5.3 numpy==1.21 owslib==0.24.1 pyproj==3.3.1 scipy==1.6.3 shapely==1.7.1 pyshp==2.3.1
 
       - name: Coverage packages
         id: coverage

INSTALL

@@ -72,7 +72,7 @@ Further information about the required dependencies can be found here:
 **pyshp** 2.3 or later (https://pypi.python.org/pypi/pyshp)
     Pure Python read/write support for ESRI Shapefile format.
 
-**pyproj** 3.1.0 or later (https://github.com/pyproj4/pyproj/)
+**pyproj** 3.3.1 or later (https://github.com/pyproj4/pyproj/)
     Python interface to PROJ (cartographic projections and coordinate transformations library).
 
 Optional Dependencies

environment.yml

@@ -12,9 +12,9 @@ dependencies:
   - numpy>=1.21
   - shapely>=1.7.1
   - pyshp>=2.3
-  - pyproj>=3.1.0
+  - pyproj>=3.3.1
   # The testing label has the proper version of freetype included
-  - conda-forge/label/testing::matplotlib-base>=3.4
+  - conda-forge/label/testing::matplotlib-base>=3.5
 
   # OWS
   - owslib>=0.24.1

lib/cartopy/_epsg.py

@@ -24,3 +24,6 @@ def __init__(self, code):
 
     def __repr__(self):
         return f'_EPSGProjection({self.epsg_code})'
+
+    def __reduce__(self):
+        return self.__class__, (self.epsg_code, )

lib/cartopy/crs.py

@@ -147,6 +147,8 @@ def __init__(self, proj4_params, globe=None):
             See :class:`~cartopy.crs.Globe` for details.
 
         """
+        self.input = (proj4_params, globe)
+
         # for compatibility with pyproj.CRS and rasterio.crs.CRS
         try:
             proj4_params = proj4_params.to_wkt()
@@ -209,13 +211,17 @@ def __hash__(self):
 
     def __reduce__(self):
         """
-        Implement the __reduce__ API so that unpickling produces a stateless
-        instance of this class (e.g. an empty tuple). The state will then be
-        added via __getstate__ and __setstate__.
-        We are forced to this approach because a CRS does not store
-        the constructor keyword arguments in its state.
+        Implement the __reduce__ method used when pickling or performing deepcopy.
         """
-        return self.__class__, (), self.__getstate__()
+        if type(self) is CRS:
+            # State can be reproduced by the proj4_params and globe inputs.
+            return self.__class__, self.input
+        else:
+            # Produces a stateless instance of this class (e.g. an empty tuple).
+            # The state will then be added via __getstate__ and __setstate__.
+            # We are forced to this approach because a CRS does not store
+            # the constructor keyword arguments in its state.
+            return self.__class__, (), self.__getstate__()
 
     def __getstate__(self):
         """Return the full state of this instance for reconstruction

lib/cartopy/tests/test_crs.py

@@ -254,11 +254,11 @@ def test_utm(self):
 
 @pytest.fixture(params=[
     [ccrs.PlateCarree, {}],
-    [ccrs.PlateCarree, dict(
-        central_longitude=1.23)],
-    [ccrs.NorthPolarStereo, dict(
-        central_longitude=42.5,
-        globe=ccrs.Globe(ellipse="helmert"))],
+    [ccrs.PlateCarree, dict(central_longitude=1.23)],
+    [ccrs.NorthPolarStereo, dict(central_longitude=42.5,
+                                 globe=ccrs.Globe(ellipse="helmert"))],
+    [ccrs.CRS, dict(proj4_params="3088")],
+    [ccrs.epsg, dict(code="3088")]
 ])
 def proj_to_copy(request):
     cls, kwargs = request.param

pyproject.toml

@@ -45,7 +45,7 @@ dependencies = [
     "shapely>=1.7",
     "packaging>=20",
     "pyshp>=2.3",
-    "pyproj>=3.1.0",
+    "pyproj>=3.3.1",
 ]
 dynamic = ["version"]