Python 中是否有一个函数与等于运算符执行相同的操作 [英] Is there a function in Python that does the same thing as the equals operator

问题描述

由于我目前对 Python 语法的理解，我遇到了一个问题，我需要将变量设置为一个值但不使用任何运算符.我必须使用函数.

Due to my current understanding of Python's syntax, I have run into an issue where I need to set a variable to a value but without using any operators. I have to use functions.

考虑这个场景

class Senario:
    x: str = ''
    y: str = ''
    
    set_global_variable(self, set_variable, val: str)
        # some verification code and modifications
        set_variable(val)

    set_x(self, val: str)
        self.set_global_variable(setX, val)

    set_x(self, val: str)
        self.set_global_variable(lambda new_x: self.x = new_x, val)

像这样设置变量的好处是添加新变量不需要为新的setter方法复制粘贴一堆验证码.它更模块化.问题是这样的程序无法运行，因为 lambdas 不能使用运算符.

The benefit of setting variables like this is that adding a new variable doesn't require copying and pasting a bunch of verification code for the new setter method. It is more modular. The problem is that such a program doesn't run because lambdas can't use operators.

错误是 self.set_global_variable(lambda new_x: self.x --> = <-- new_x, val)

The error is self.set_global_variable(lambda new_x: self.x --> = <-- new_x, val)

这不是正确的语法.为了运行这样的程序，我需要某种与 = 运算符完全相同的 equals 方法.实现方式如下.

It's not the proper syntax. In order to run a program like this, I need some sort of equals method that does the exact same thing as the = operator. The implementation would work as follows.

set_x(self, val: str)
    self.set_global_variable(lambda new_x: self.x.equals(new_x), val)

Python 中是否有内置方法可以执行此操作，如果仅适用于字符串?如果没有，是否可以轻松编写方法?可以将一个变量作为输入并将该精确变量设置为一个新值，而不是它的本地副本?

Is there a built-in method in Python to do this, if only for strings? If not, can a method be easily written? One that can take a variable as input and set that exact variable to a new value, and not a local copy of it?

推荐答案

最简单的解决方案可能是使用执行赋值的本地函数，如下所示:

The easiest solution may be to use a local function that performs the assignment, as follows:

def set_x(self, val: str):
    def _set_variable(new_x):
        self.x = new_x
    self.set_global_variable(_set_variable, val)

但是，如果您想使用 lambda 表达式，您可以尝试使用 setattr python 的内置函数，它满足你的要求:

However, if you want to use a lambda expression, you can try using the setattr built-in function of python, which does what you asked for:

def set_x(self, val: str):
    self.set_global_variable(lambda new_x: setattr(self, "x", new_x), val)

更通用的解决方案可能是将字段名称传递给 set_global_variable 并使用 setattr 执行赋值，如下所示:

A more general solution could be to pass the field name to the set_global_variable and use setattr to perform the assignment, as follows:

def set_global_variable(self, variable_name, val):
    # some verification code and modifications
    setattr(self, variable_name, val)

def set_x(self, val: str):
    set_global_variable("x", val)

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