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我正在开发一个将变量初始化为默认值的应用程序。

用户可以随时更改这些值。用户应该可以随时将部分或全部变量重置为默认值。

最好的解决方法是什么？

这将是一个解决方案，但我觉得它不是最理想的。你能告诉我我的感觉是否正确以及我怎样才能做得更好吗？

A_DEFAULT = "A_def"
B_DEFAULT = "B_def"
C_DEFAULT = "C_def"

class BusinessLogic_1(object):
    def __init__(self):
        self.setVariablesToDefault()
    def setVariablesToDefault(self, variableNames=None):
        # pass None to set all Variables to default
        variableNames = variableNames or ["A","B","C"]
        if "A" in variableNames:
            self.A = A_DEFAULT
        if "B" in variableNames:
            self.B = B_DEFAULT
        if "C" in variableNames:
            self.C = C_DEFAULT
    def printVariables(self):
        print  "A: %s, B: %s, C: %s" % (self.A, self.B, self.C)

if __name__ == "__main__":
    print "0: Initialize"
    businessLogic_1 = BusinessLogic_1()
    businessLogic_1.printVariables()

    print "Change A,B,C and then reset A,C"
    businessLogic_1.A = "A_new"
    businessLogic_1.B = "B_new"
    businessLogic_1.C = "C_new"
    businessLogic_1.printVariables()
4

2 回答 2

1

这可能是一个解决方案。这是一种将变量名称作为字符串传递，然后通过这些名称访问它们的方法。对象可以同时有多个名称，但名称总是指向一个对象（在给定的时间点）。

class classWithVariablesThatHaveDefaultValues(object):

    def __init__(self, some, example, variables, defaultValuesDict):
        self.some = some
        self.example = example
        self.variables = variables
        self.dictionaryWithDefaultValues = defaultValuesDict

    def resetValues(self, *listOfVariables):
        for variable in listOfVariables:
            for key in self.dictionaryWithDefaultValues:
                if key == variable:            
                    vars(self)[key] = self.dictionaryWithDefaultValues[key]

if __name__ == "__main__":

    defaultValuesDict = {"some":4, "example":5, "variables":6}
    exampleObject = classWithVariablesThatHaveDefaultValues(1, 2, 3, defaultValuesDict)
    exampleObject.some = 15
    print exampleObject.some, exampleObject.example, exampleObject.variables
    exampleObject.resetValues("example", "some")
    print exampleObject.some, exampleObject.example, exampleObject.variables

输出是：

15 2 3

4 5 3

于 2012-12-10T07:06:25.880 回答
0

您可以通过与工作方式非常相似的方式实现它decimal.localcontext()，但根据您的用例，这可能不合适。这将允许您操作和调用反映更新值的原始对象上的任何方法，并在with块的末尾将它们重置为输入时的值。

from contextlib import contextmanager

class A(object):
    def __init__(self):
        self.a = 3
        self.b = 5
    def display(self):
        return self.a, self.b

a = A()

@contextmanager
def mycontext(obj):
    old_a = obj.a
    old_b = obj.b
    yield obj
    obj.a = old_a
    obj.b = old_b


print 'before:', a.display()
with mycontext(a) as obj:
    print 'entered:', a.display()
    a.a = 3
    a.b = 7
    print 'changed:', a.display()


print 'hopefully original', a.display()

before: (3, 5)
entered: (3, 5)
changed: (3, 7)
hopefully original (3, 5)
于 2012-11-15T17:25:11.870 回答