python 函数里面使用[]作为默认参数时,会提示Default Argument Value is mutable(默认参数值是可以改变的) 每次执行函数的时候,可能会不断累加(如果函数里面有append或extend方法),这其实不是我们想要的 解决…
Default argument value is mutable 这是因为,在Python中,当函数参数使用可变类型(如列表、字典、集合等)作为默认值时,可能会遇到一个问题,即这些默认值在函数被多次调用时可能会被意外修改。这是因为Python在函数定义时计算一次默认值,并在之后的调用中重复使用这些默认值,而不是每次调用时都重新创建它们。 示例问题...
警告:Default Argument Value is mutable 产生原因 参数赋值为可变对象(mutableobject),比如list; 函数参数的初值只会被计算一次。 参考案例 解决方法
2、The Python Tutorial The default value is evaluated only once. This makes a difference when the default is a mutable object such as a list, dictionary, or instances of most classes. For example, the following function accumulates the arguments passed to it on subsequent calls 解决方案: 参考...
@文心快码BaiduComatedefault argument value is mutable 文心快码BaiduComate 1. 解释什么是默认参数值 在Python中,函数定义时可以指定某些参数具有默认值。当调用函数时,如果未提供这些具有默认值的参数,则函数将使用这些默认值进行执行。默认参数值在函数定义时计算一次,并在函数多次调用之间保持不变,除非显式地通过...
Default argument values are evaluated only once, at function definition. Consequently, any modification to that value will affect all subsequent calls. def set_draw_airports(self, value, port_type=["small_airport"], reload=True): def set...
String Type:The default value is an empty string (""). Boolean Type:The default value isfalse. Pointers and Interfaces:The default value isnil. Structs:Each field of the struct is initialized with its respective default value. Examples of Slice Default Values ...
The following used to work: m = ConcreteModel() model.p = Param(mutable=True) assert model.p.value == None This now results in an error when model.p.value is accessed with the message "The Param value is undefined and no default value is...
Important warning:The default value is evaluated only once.This makes a difference when the default is a mutable object such as a list, dictionary, or instances of most classes. For example, the following function accumulates the arguments passed to it on subsequent calls: ...
Documentation The example: dataclasses.html#mutable-default-values @dataclass class D: x: list = [] # This code raises ValueError def add(self, element): self.x += element not only raises the ValueError being discussed, but also an unwan...