Validate declarative interface attributes

src/metpy/plots/declarative.py

@@ -6,6 +6,7 @@
 import contextlib
 import copy
 from datetime import datetime, timedelta
+from difflib import get_close_matches
 from itertools import cycle
 import re
 
@@ -508,6 +509,33 @@ def plot_kwargs(data):
     return kwargs
 
 
+class ValidationMixin:
+    """Provides validation of attribute names when set by user."""
+
+    def __setattr__(self, name, value):
+        """Set only permitted attributes."""
+        allowlist = ['ax',
+                     'data',
+                     'handle',
+                     'notify_change',
+                     'panel'
+                     ]
+
+        allowlist.extend(self.trait_names())
+        if name in allowlist or name.startswith('_'):
+            super().__setattr__(name, value)
+        else:
+            closest = get_close_matches(name, allowlist, n=1)
+            if closest:
+                alt = closest[0]
+                suggest = f" Perhaps you meant '{alt}'?"
+            else:
+                suggest = ''
+            obj = self.__class__
+            msg = f"'{name}' is not a valid attribute for {obj}." + suggest
+            raise AttributeError(msg)
+
+
 class MetPyHasTraits(HasTraits):
     """Provides modification layer on HasTraits for declarative classes."""
 
@@ -524,7 +552,7 @@ class Panel(MetPyHasTraits):
 
 
 @exporter.export
-class PanelContainer(MetPyHasTraits):
+class PanelContainer(MetPyHasTraits, ValidationMixin):
     """Collects panels and set complete figure related settings (e.g., size)."""
 
     size = Union([Tuple(Union([Int(), Float()]), Union([Int(), Float()])),
@@ -600,7 +628,7 @@ def copy(self):
 
 
 @exporter.export
-class MapPanel(Panel):
+class MapPanel(Panel, ValidationMixin):
     """Set figure related elements for an individual panel.
 
     Parameters that need to be set include collecting all plotting types
@@ -1202,7 +1230,7 @@ class ColorfillTraits(MetPyHasTraits):
 
 
 @exporter.export
-class ImagePlot(PlotScalar, ColorfillTraits):
+class ImagePlot(PlotScalar, ColorfillTraits, ValidationMixin):
     """Make raster image using `~matplotlib.pyplot.imshow` for satellite or colored image."""
 
     @observe('colormap', 'image_range')
@@ -1257,7 +1285,7 @@ def _build(self):
 
 
 @exporter.export
-class ContourPlot(PlotScalar, ContourTraits):
+class ContourPlot(PlotScalar, ContourTraits, ValidationMixin):
     """Make contour plots by defining specific traits."""
 
     linecolor = Unicode('black')
@@ -1306,7 +1334,7 @@ def _build(self):
 
 
 @exporter.export
-class FilledContourPlot(PlotScalar, ColorfillTraits, ContourTraits):
+class FilledContourPlot(PlotScalar, ColorfillTraits, ContourTraits, ValidationMixin):
     """Make color-filled contours plots by defining appropriate traits."""
 
     @observe('contours', 'colorbar', 'colormap')
@@ -1478,7 +1506,7 @@ def draw(self):
 
 
 @exporter.export
-class BarbPlot(PlotVector):
+class BarbPlot(PlotVector, ValidationMixin):
     """Make plots of wind barbs on a map with traits to refine the look of plotted elements."""
 
     barblength = Float(default_value=7)
@@ -1514,7 +1542,7 @@ def _build(self):
 
 
 @exporter.export
-class PlotObs(MetPyHasTraits):
+class PlotObs(MetPyHasTraits, ValidationMixin):
     """The highest level class related to plotting observed surface and upperair data.
 
     This class collects all common methods no matter whether plotting a upper-level or

tests/plots/test_declarative.py

@@ -1668,3 +1668,21 @@ def test_drop_traitlets_dir():
         assert not dir(plot_obj())[0].startswith('_')
         assert 'cross_validation_lock' in dir(plot_obj)
         assert 'cross_validation_lock' not in dir(plot_obj())
+
+
+@needs_cartopy
+def test_attribute_error_suggest():
+    """Test that a mistyped attribute name raises an exception with fix."""
+    with pytest.raises(AttributeError) as excinfo:
+        panel = MapPanel()
+        panel.pots = []
+    assert "Perhaps you meant 'plots'?" in str(excinfo.value)
+
+
+@needs_cartopy
+def test_attribute_error_no_suggest():
+    """Test that a mistyped attribute name raises an exception w/o a fix."""
+    with pytest.raises(AttributeError) as excinfo:
+        panel = MapPanel()
+        panel.galaxy = 'Andromeda'
+    assert 'Perhaps you meant' not in str(excinfo.value)