safe install

Author: mmatera

pymathics/vectorizedplot/__init__.py

@@ -24,7 +24,12 @@
 
 from pymathics.vectorizedplot.version import __version__
 
-from .plot_plot3d import ContourPlot3D, ParametricPlot3D, SphericalPlot3D
+ALREADY_INSTALLED = True
+try:
+    from .plot_plot3d import ContourPlot3D, ParametricPlot3D, SphericalPlot3D
+except ModuleNotFoundError:
+    ALREADY_INSTALLED = False
+
 
 # To be recognized as an external mathics module, the following variable
 # is required:
@@ -40,9 +45,16 @@
 
 
 __all__ = (
-    "ContourPlot3D",
-    "ParametricPlot3D",
-    "SphericalPlot3D",
-    "__version__",
-    "pymathics_version_data",
+    (
+        "ContourPlot3D",
+        "ParametricPlot3D",
+        "SphericalPlot3D",
+        "__version__",
+        "pymathics_version_data",
+    )
+    if ALREADY_INSTALLED
+    else (
+        "__version__",
+        "pymathics_version_data",
+    )
 )