Below is some sample code straight from the MayaVI website on using sliders. Try putting in a number outside of the slider range for a fatal error:
from numpy import arange, pi, cos, sin
from traits.api import HasTraits, Range, Instance, \
on_trait_change
from traitsui.api import View, Item, Group
from mayavi.core.api import PipelineBase
from mayavi.core.ui.api import MayaviScene, SceneEditor, \
MlabSceneModel
dphi = pi/1000.
phi = arange(0.0, 2*pi + 0.5*dphi, dphi, 'd')
def curve(n_mer, n_long):
mu = phi*n_mer
x = cos(mu) * (1 + cos(n_long * mu/n_mer)*0.5)
y = sin(mu) * (1 + cos(n_long * mu/n_mer)*0.5)
z = 0.5 * sin(n_long*mu/n_mer)
t = sin(mu)
return x, y, z, t
class MyModel(HasTraits):
n_meridional = Range(0, 30, 6, )#mode='spinner')
n_longitudinal = Range(0, 30, 11, )#mode='spinner')
scene = Instance(MlabSceneModel, ())
plot = Instance(PipelineBase)
# When the scene is activated, or when the parameters are changed, we
# update the plot.
@on_trait_change('n_meridional,n_longitudinal,scene.activated')
def update_plot(self):
x, y, z, t = curve(self.n_meridional, self.n_longitudinal)
if self.plot is None:
self.plot = self.scene.mlab.plot3d(x, y, z, t,
tube_radius=0.025, colormap='Spectral')
else:
self.plot.mlab_source.set(x=x, y=y, z=z, scalars=t)
# The layout of the dialog created
view = View(Item('scene', editor=SceneEditor(scene_class=MayaviScene),
height=250, width=300, show_label=False),
Group(
'_', 'n_meridional', 'n_longitudinal',
),
resizable=True,
)
my_model = MyModel()
my_model.configure_traits()
How can I improve this code to disallow users from triggering this fatal error? I think a line that could deactivate the entry box (such as setDisabled(True)) could work, or remove it entirely - but I'm not sure how to implement it within the traitsui methods.
After lots of trial and error, this appears to be a bug in the default Range() mode of Traitsui, at least in the case for Mac OS X (I'm running High Sierra, 10.13.3).
The solution is to alter the default mode to one that looks and acts identical, minus crashing the program:
n_meridional = Range(0, 30, 6, mode='slider')