在Python中布尔值不会改变

Question

我正在尝试用Python创建一个程序，要求用户输入一个字符串(最好是小写的)，然后将该字符串转换为句子大小写。但是，我用来检查下一个字母是否需要大写的布尔值不会被设置为False，尽管满足'if‘语句所需的条件。

    class SentenceCaseProgram(object):
        def __init__(self, isPunctuation, isSpace, sentence, new_sentence):
            self.isPunctuation = isPunctuation
            self.sentence = sentence
            self.new_sentence = new_sentence
            self.isSpace = isSpace
            self.count = 0
        def Input(self):
            self.sentence = str(input("Type in a sentence (with punctuation) entirely in lowercase. "))
        def SentenceCase(self):
            for letter in self.sentence:
                print(self.isPunctuation)
                if self.count == 0:
                    letter = letter.capitalize()
                if letter is ' ':
                    self.isSpace = True
                if (self.isPunctuation == True) and (letter in 'abcdefghijklmnopqrstuvwxyz'):
                    letter = letter.capitalize()
                    self.isPunctuation = letter is '.' or '!' or '?' or ')'
                if letter is 'i' and self.isSpace is True:
                    letter = letter.capitalize()
                    self.isSpace = False
                self.count += 1
                if letter == '.' or '!' or '?' or ')':
                    self.isPunctuation = True
                else:
                    self.isPunctuation = False
                self.new_sentence += letter
        def Print(self):
            print("Your sentence in sentence case is '%s'" % self.new_sentence)
        def Main(self):
            self.__init__(False, False, "", "")
            self.Input()
            self.SentenceCase()
            self.Print()
    app = SentenceCaseProgram(False, False, "", "")
    app.Main()

当我运行程序时，程序要求输入，然后将句子中的每个字母大写，除了第一个循环之外，self.isPunctuation布尔值将始终设置为True。

Answer 1

请使用==，而不要使用is来比较字符串

letter is '.' or '!' or '?' or ')'应该是

letter == '.' or letter == '!' or letter == '?' or letter == ')'

或

letter in '.!?)'