python块级作用域和函数作用域

 python块级作用域和函数作用域

(1)#Python中无块级作用域:
#java/c#  不可以执行下面代码
#python/javascript  可以执行

if 1 == 1:
    name = 'python'

print(name)


for i in range(10):
    name = i

print(name)


(2)#Python中以函数为作用域:
def func():
    name = 'python'

func()
print(name)

name = 'python'

def f1():
    name = 'linux'
    print(name)

f1()

(3)#python作用域链，由内往外找，直到找不到报错
name = 'python'

def f1():
    name = 'a'
    def f2():
        name = 'b'
        print(name)
    f2()

f1()


(4)#python的作用域在执行之前已经确定

name = 'python'

def f1():
    print(name)


def f2():
    name = 'linux'
    f1()

f2()


(5)#在函数未执行之前作用域已经确定了
name = 'python'

def f1():
    print(name)

def f2():
    name = 'linux'
    return f1

f2()

(6)#列表解析
li = [x+100 for x in range(10)]
li = [x+100 for x in range(10) if x > 6]
print(li)

li = [ lambda : x for x in range(10)]
	#li列表
	#li列表中的元素：[函数,函数,函数....]
	#函数在没有执行前，内部代码部执行
	#li[0],函数
	#函数()
	#返回值是???
print(li)
ret = li[0]()
print(ret)


(7)上面的表达式就相当于下面
l1 = []

for i in range(10):

    def f1():
        return i

    l1.append(f1)

ret = l1[0]()
print(ret)
ret1 = l1[1]()
print(ret1)


(8)# 只要执行了就能拿到值
l1 = []

for i in range(10):

    def f1(x=i):
        return x

    l1.append(f1)

ret = l1[0]()
print(ret)
ret = l1[1]()
print(ret)
ret = l1[2]()
print(ret)