更清晰的来说,对于ypython 解释器必须要界定他的作用域范围,而由于他先检测到赋值操作,所以将y界定成了local作用域;当他开始处理y + 5时,会尝试读取local作用域的y值,结果发现在赋值前被引用了(referenced before assignment)。 实际只需要将y = y + 5修改为x = y + 5,就不会报错了。而更加正确的
Python resolves variable names using the LEGB rule: Local, Enclosing, Global, Built-in scopes, in that order. When a variable is referenced, Python searches these scopes sequentially. This example demonstrates each scope level. Understanding LEGB is fundamental to Python programming. legb.py # G...
#!/usr/bin/python2.7#File: demo.py#Author: lxw#Time: 2014-09-01number= 5deffunc0():#It's OK to reference.printnumberdeffunc1():#new local variable.number = 10printnumberdeffunc2():#global declaration.globalnumberprintnumber number= 10printnumberprint"Before calling any function, number ...
An attempt to print a local variable outside its scope will raise the NameError exception. Example: Local Variable Copy def greet(): name = 'Steve' print('Hello ', name) greet() print(name) #NameError Try it Here, name is a local variable for the greet() function and is not ...
python 中变量的作用域经常让我感到很迷 In Python, on the other hand, variables declared in if-statements, for-loop blocks, and while-loop blocks are not local variables, and stay in scope outside of the block. Thus we say that C++ has “block-level” scoping, while Python uses only “...
This means that the scope of a local variable is limited to the block. Their life is limited to the amount of time, the block in which they are defined, spends executing. In Python, variables are assumed to be local unless they are explicitly declared to be global. This is a good ...
http://www.crifan.com/summary_python_variable_effective_scope/ 解释python中变量的作用域 示例: 1、代码版 #!/usr/bin/python # -*- coding: utf-8 -*- """ --- Function: 【整理】Python中:self和init__的含义 + 为何要有self和__init__ http://www.crifan.com/summary_the_meaning...
Python Advanced Topics List comprehension Python Lambda/Anonymous Function Python Iterators Python Generators Python Namespace and Scope Python Closures Python Decorators Python @property decorator Python RegEx Python Date and Time Python datetime Python strftime() Python strptime() How to get current date...
http://www.crifan.com/summary_python_variable_effective_scope/ 解释python中变量的作用域 示例: 1、代码版 1#!/usr/bin/python2#-*- coding: utf-8 -*-3"""4---5Function:6【整理】Python中:self和init__的含义 + 为何要有self和__init__7http://www.crifan.com/summary_the_meaning_of_self_...
定义variable() 使用的变量创建函数的范围。 用法 @tf_contextlib.contextmanagertf.variable_creator_scope( variable_creator ) 参数 variable_creator过去的创造者 生成(Yield) 创建者处于活动状态的范围 variable_creator 应该是具有以下签名的函数: defvariable_creator(next_creator, **kwargs) ...