为什么在实例化一个_repr__\u方法时会出现语法错误

Question

当我使用我拥有的repr方法实例化一个类时，我收到以下错误

当我删除repr时，它可以正常工作：

repr已删除

class Wide():
    def __init__(self,  XfromLeftEdge = 141.0, YfromTopEdge = 300.0, Width = 1551.0, Height = 800.0 ):
        self.XfromLeftEdge =XfromLeftEdge
        self.YfromTopEdge =YfromTopEdge
        self.Width = Width
        self.Height = Height

    def objOne(self): #XfromLeftEdge, YfromTopEdge, Width, Height
        return XfromLeftEdge, YfromTopEdge, Width, Height

a = Wide()
print(a)

返回：

<__main__.Wide object at 0x7faec1ed48b0>
(base) user SDNrig 6 % 

带有报告

class Wide():
    def __init__(self,  XfromLeftEdge = 141.0, YfromTopEdge = 300.0, Width = 1551.0, Height = 800.0 ):
        self.XfromLeftEdge =XfromLeftEdge
        self.YfromTopEdge =YfromTopEdge
        self.Width = Width
        self.Height = Height

    def objOne(self): #XfromLeftEdge, YfromTopEdge, Width, Height
        return XfromLeftEdge, YfromTopEdge, Width, Height

    def __repr__(self):
        return '{}, {}, {}, {}'.format(self.XfromLeftEdge = XfromLeftEdge, self.YfromTopEdge = YfromTopEdge, self.Width = Width, self.Height = Height)

    def __str__(self):
        return 'instance object of wide ROI object, XfromLeftEdge:{}, YfromTopEdge: {}, Width: {}, Height: {}'.format(
            self.XfromLeftEdge = XfromLeftEdge,
            self.YfromTopEdge = YfromTopEdge,
            self.Width = Width,
            self.Height = Height)
 
a = Wide()
print(a)

返回

(base) user SDNrig 6 % /usr/local/bin/python3 "/Users/.../Desktop/SDNrig 6/play_f.py"
  File "/Users/.../Desktop/SDNrig 6/play_f.py", line 15
    return '{}, {}, {}, {}'.format(self.XfromLeftEdge = XfromLeftEdge, self.YfromTopEdge = YfromTopEdge, self.Width = Width, self.Height = Height)
                                   ^
SyntaxError: expression cannot contain assignment, perhaps you meant "=="?

所需输出

我希望看到打印（a）给出参数及其值

Answer 1

您不需要格式字符串中的赋值。 使用以下命令：

class Wide():
def __init__(self,  XfromLeftEdge = 141.0, YfromTopEdge = 300.0, Width = 1551.0, Height = 800.0 ):
    self.XfromLeftEdge =XfromLeftEdge
    self.YfromTopEdge =YfromTopEdge
    self.Width = Width
    self.Height = Height

def objOne(self): #XfromLeftEdge, YfromTopEdge, Width, Height
    return XfromLeftEdge, YfromTopEdge, Width, Height

def __repr__(self):
    return f"Wide({self.XfromLeftEdge}, {self.YfromTopEdge}, {self.Width}, {self.Height})"

def __str__(self):
    return f'instance object of wide ROI object, XfromLeftEdge:{self.XfromLeftEdge}, YfromTopEdge: {self.YfromTopEdge}, Width: {self.Width}, Height: {Self.Height}'

这还将使用f字符串语法以提高可读性

Answer 2

此代码将解决您的错误

class Wide():
    def __init__(self,  XfromLeftEdge = 141.0, YfromTopEdge = 300.0, Width = 1551.0, Height = 800.0 ):
        self.XfromLeftEdge =XfromLeftEdge
        self.YfromTopEdge =YfromTopEdge
        self.Width = Width
        self.Height = Height

    def objOne(self): #XfromLeftEdge, YfromTopEdge, Width, Height
        return XfromLeftEdge, YfromTopEdge, Width, Height

    def __repr__(self):
        return '{}, {}, {}, {}'.format(self.XfromLeftEdg, self.YfromTopEdge, self.Width, self.Height)

    def __str__(self):
        return 'instance object of wide ROI object, XfromLeftEdge:{}, YfromTopEdge: {}, Width: {}, Height: {}'.format(
            self.XfromLeftEdge,
            self.YfromTopEdge,
            self.Width,
            self.Height)

a = Wide()
print(a)

或

class Wide():
    def __init__(self,  XfromLeftEdge = 141.0, YfromTopEdge = 300.0, Width = 1551.0, Height = 800.0 ):
        self.XfromLeftEdge =XfromLeftEdge
        self.YfromTopEdge =YfromTopEdge
        self.Width = Width
        self.Height = Height

    def objOne(self): #XfromLeftEdge, YfromTopEdge, Width, Height
        return XfromLeftEdge, YfromTopEdge, Width, Height

    def __repr__(self):
        return '{XfromLeftEdg}, {YfromTopEdge}, {Width}, {Height}'.format(XfromLeftEdg = self.XfromLeftEdg, YfromTopEdge =self.YfromTopEdge, Width = self.Width, Height =self.Height)

    def __str__(self):
        return 'instance object of wide ROI object, XfromLeftEdge:{XfromLeftEdge}, YfromTopEdge: {YfromTopEdge}, Width: {Width}, Height: {Height}'.format(
            XfromLeftEdge = self.XfromLeftEdge,
            YfromTopEdge = self.YfromTopEdge,
            Width = self.Width,
            Height = self.Height)

a = Wide()
print(a)

问题是在repr和str方法的字符串中有{}没有键，而在format方法中有一个键值对
键和值的方向被交换