带滑块输入框的traitsui Range()致命错误

Question

下面是一些直接从MayaVI网站使用滑块的示例代码。尝试为致命错误在滑块范围之外输入一个数字

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()

如何改进此代码以防止用户触发此致命错误？我认为可以禁用输入框(如setDisabled(True))的行可以工作，或者完全删除它--但我不知道如何在traitsui方法中实现它。

Answer 1

经过大量的尝试和错误，这似乎是一个错误，在默认的Range()模式的Traitsui，至少在Mac的情况下(我运行High，10.13.3)。

解决方案是将默认的mode更改为外观和行为相同的mode，减去程序崩溃：

n_meridional = Range(0, 30, 6, mode='slider')