问题出在if new_value and not self.last_value:
所以第一部分是寻找 new_value 是否具有 Truthy 值。并且它正在寻找 self.last_value 是否具有 Falsey 值。当您开始相互比较两个不同的布尔值时，这会变得很混乱。
第一部分真的是看new_value中是否有值。因此，我们可以将其与无进行比较。第二部分是真正查看两个布尔值是否匹配，因此我们可以将它们相互比较。
将线更新为这个，它应该适用于任一方向的转换。
if new_value is not None and new_value is not self.last_value:
编辑：
根据您的 cmets：
有几种方法可以跟踪相变，而无需逐个查找。
选项一：
使用一个函数来跟踪从真到假的过渡和从假到真的过渡。我们可以将值传回给打印机函数。
def test(self):
new_value = self.reader()
if new_value is not None and new_value is not self.last_value:
self.action(new_value) # Note here we are passing a value back
self.last_value = new_value
现在我们只需添加到打印机功能以查看更改。
def printer(transition):
print(f"Phase transition to: {transition}")
最终代码选项 1：
test = [True, False, False, True, True, False, True, True, False, False, False, True]
class EdgeDetector:
"""Detects False to True transitions on an external signal."""
def __init__(self, reader, action):
self.reader = reader
self.action = action
self.last_value = reader() # initialize value
def test(self):
new_value = self.reader()
if new_value is not None and new_value is not self.last_value:
self.action(new_value)
self.last_value = new_value
# simple self-test
if __name__ == '__main__':
vlist = test
vgen = (v for v in vlist) # generator for value sequence
def test_reader(): # generate test sequence
value = next(vgen)
print("Read:", value)
return value
def printer(transition):
print(f"Phase transition to: {transition}")
test_subject = EdgeDetector(test_reader, printer)
for i in range(len(vlist)-1):
test_subject.test()
选项二：
如果您想要单独的代码用于从 false 到 true 以及从 true 到 false 的转换，这就是这样做的方法。
首先在 EdgeDetector 类中，我们需要修改 init 如下：
def __init__(self, reader, action_true, action_false): #Note the second action here
self.reader = reader
self.action_true = action_true
self.action_false = action_false # We set it just like the previous one.
self.last_value = reader()
然后我们就可以更新测试代码了。
def test(self):
new_value = self.reader()
if new_value is not None and new_value is not self.last_value:
if new_value:
self.action_true()
else:
self.action_false()
self.last_value = new_value
然后我们修改printer语句，添加第二条：
def printer_true():
print("Phase transition to true")
def printer_false():
print("Phase transition to false")
最后EdgeDetector的初始化需要更新。
test_subject = EdgeDetector(test_reader, printer_true, printer_false)
选项 2 的最终代码
test = [True, False, False, True, True, False, True, True, False, False, False, True]
class EdgeDetector:
"""Detects False to True transitions on an external signal."""
def __init__(self, reader, action_true, action_false):
self.reader = reader
self.action_true = action_true
self.action_false = action_false
self.last_value = reader() # initialize value
def test(self):
new_value = self.reader()
if new_value is not None and new_value is not self.last_value:
self.action(new_value)
self.last_value = new_value
# simple self-test
if __name__ == '__main__':
vlist = test
vgen = (v for v in vlist) # generator for value sequence
def test_reader(): # generate test sequence
value = next(vgen)
print("Read:", value)
return value
def printer_true():
print(f"Phase transition to true")
def printer_false():
print(f"Phase transition to false")
test_subject = EdgeDetector(test_reader, printer_true, printer_false)
for i in range(len(vlist)-1):
test_subject.test()