Merge remote-tracking branch 'origin/main' into main

Author: tomvanmele

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Added `faces_where`, `faces_where_predicate`, `cells_where`, `cells_where_predicate` to `compas.datastructures.HalfFace`.
 * Added `VolMeshArtist` to registered Blender artists.
 * Added `3.1` to supported versions for Blender installer.
+* Added `compas.artist.NoArtistContextError`.
 
 ### Changed
 
@@ -51,6 +52,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Fixed `compas_blender.artists.VolMeshArtist.draw` and `compas_blender.artists.VolMeshArtist.draw_cells`.
 * Fixed `compas_ghpython.artists.VolMeshArtist.draw` and `compas_ghpython.artists.VolMeshArtist.draw_cells`.
 * Fixed `compas_rhino.artists.VolMeshArtist.draw` and `compas_rhino.artists.VolMeshArtist.draw_cells`.
+* Improved error messages when artist instance cannot be created.
 * Fixed bug in `compas_rhino.conversions.RhinoCurve.to_compas`.
 * Fixed bug in `compas_rhino.conversions.RhinoSurface.to_compas`.
 

src/compas/artists/__init__.py

@@ -39,6 +39,7 @@
     :nosignatures:
 
     DataArtistNotRegistered
+    NoArtistContextError
 
 
 Pluggables
@@ -58,6 +59,7 @@
 from __future__ import division
 
 from .exceptions import DataArtistNotRegistered
+from .exceptions import NoArtistContextError
 from .artist import Artist
 from .curveartist import CurveArtist
 from .meshartist import MeshArtist
@@ -77,6 +79,7 @@
 
 __all__ = [
     'DataArtistNotRegistered',
+    'NoArtistContextError',
     'Artist',
     'CurveArtist',
     'MeshArtist',

src/compas/artists/artist.py

@@ -7,9 +7,10 @@
 from collections import defaultdict
 
 import compas
-from compas.artists import DataArtistNotRegistered
-from compas.plugins import pluggable
+from compas.artists.exceptions import DataArtistNotRegistered
+from compas.artists.exceptions import NoArtistContextError
 from compas.plugins import PluginValidator
+from compas.plugins import pluggable
 
 from .colordict import DescriptorProtocol
 
@@ -45,6 +46,9 @@ def _get_artist_cls(data, **kwargs):
     else:
         Artist.CONTEXT = identify_context()
 
+    if Artist.CONTEXT is None:
+        raise NoArtistContextError()
+
     dtype = type(data)
     cls = None
 
@@ -85,11 +89,15 @@ class Artist(object):
     CONTEXT = None
     ITEM_ARTIST = defaultdict(dict)
 
-    def __new__(cls, *args, **kwargs):
+    def __new__(cls, item, **kwargs):
         if not Artist.__ARTISTS_REGISTERED:
             register_artists()
             Artist.__ARTISTS_REGISTERED = True
-        cls = _get_artist_cls(args[0], **kwargs)
+
+        if item is None:
+            raise ValueError('Cannot create an artist for None. Please ensure you pass a instance of a supported class.')
+
+        cls = _get_artist_cls(item, **kwargs)
         PluginValidator.ensure_implementations(cls)
         return super(Artist, cls).__new__(cls)
 

src/compas/artists/exceptions.py

@@ -5,3 +5,13 @@
 
 class DataArtistNotRegistered(Exception):
     """Exception that is raised when no artist is registered for a given data type."""
+
+
+class NoArtistContextError(Exception):
+    """Exception that is raised when no artist context is assigned is registered for a given data type."""
+    def __init__(self):
+        error_message = "No context defined."
+        error_message += "\n\nThis usually means that the script that you are running requires"
+        error_message += "\na CAD environment but it is being ran as a standalone script"
+        error_message += "\n(ie. from the command line or code editor)."
+        super(NoArtistContextError, self).__init__(error_message)