以一个简单的外汇计算器应用程序为例。在
我可以使用traitlets
定义我的模型:
from traitlets import HasTraits, Float, observe, Enum
import math
class FXModel(HasTraits):
domestic_qty = Float()
foreign_qty = Float()
fx_rate = Float(float('nan')) # in units of domestic_qty/foreign_qty
lock = Enum(['domestic', 'foreign'], default_value='domestic')
_calculating = Enum([None, 'domestic', 'foreign'], default_value=None)
def calc_foreign(self):
if not math.isnan(self.fx_rate):
self._calculating = 'foreign'
self.foreign_qty = self.domestic_qty / self.fx_rate
self._calculating = None
def calc_domestic(self):
if not math.isnan(self.fx_rate):
self._calculating = 'domestic'
self.domestic_qty = self.foreign_qty * self.fx_rate
self._calculating = None
@observe('domestic_qty')
def on_domestic(self, change):
if self._calculating is None:
self.calc_foreign()
@observe('foreign_qty')
def on_foreign(self, change):
if self._calculating is None:
self.calc_domestic()
@observe('fx_rate')
def on_fxrate(self, change):
if self.lock == 'domestic':
self.calc_foreign()
else:
self.calc_domestic()
以及相应的简单的基于“打印”的视图:
^{2}$其工作原理如下:
>> fx_model = FXModel(domestic_qty = 100., fx_rate = 200.)
>> fx_view = FXView(fx_model)
>> fx_view.show()
domestic_qty: 100
foreign_qty: 0.5
fx_rate: 200
lock: domestic
>> fx_model.fx_rate = 195.
>> fx_view.show()
domestic_qty: 100
foreign_qty: 0.5128
fx_rate: 195
lock: domestic
我还使用ipywidgets创建了一个视图:
import ipywidgets as widgets
domestic_label = widgets.Label("Domestic quantity")
domestic_field = widgets.FloatText()
foreign_label = widgets.Label("Foreign quantity")
foreign_field = widgets.FloatText()
fx_label = widgets.Label("Exchange rate (domestic/foreign)")
fx_field = widgets.FloatText()
lock_label = widgets.Label("If rates change, keep ")
lock_field = widgets.Dropdown(options=["domestic", "foreign"])
lock_label_post = widgets.Label('fixed')
ipyview = widgets.HBox([widgets.VBox([domestic_label, foreign_label, fx_label, lock_label]),
widgets.VBox([domestic_field, foreign_field, fx_field, widgets.HBox([lock_field, lock_label_post])])])
看上去真不错:
我的问题是:如何将模型和ipyview“绑定”在一起?我对enaml
有一些经验,通过:=
和朋友可以做到这一点。在
用ipywidgets
做这件事的最好方法是什么?在
好问题!我在一个ipywidgets问题上发布了一个答案:https://github.com/jupyter-widgets/ipywidgets/issues/2296
下面是如何使用ipywidget视图,使用post中的小部件创建一个自定义视图。小部件调用的键是绑定值。在
我要指出的是Param提倡这种分离已经有一段时间了,@jbednar已经指出ipywidgets也可以实现方便函数来支持这种模式。我认为这是一个好主意-有一些简单的方便函数,这些函数是从接受HasTraits类的交互函数中升级的,它可以对它进行反省,并为常见情况下的不同特征提供默认窗口小部件。在
相关问题 更多 >
编程相关推荐