python yield和yield from的区别

def gen(*args, **kwargs):
    for item in args:
        yield item


def gen2(*args, **kwargs):
    for item in args:
        yield from item


if __name__ == '__main__':
    astr = "ABC"
    alist = [1, 2, 3]
    adict = {"nba": "湖人", "age": 18}
    # generate
    agen = (i for i in range(4, 8))

    new_list = gen(astr, alist, adict, agen)
    new_list2 = gen2(astr, alist, adict, agen)
    print(list(new_list))
    print(list(new_list2))

结果如下：

['ABC', [1, 2, 3], {'nba': '湖人', 'age': 18}, <generator object <genexpr> at 0x108192990>]     

['A', 'B', 'C', 1, 2, 3, 'nba', 'age', 4, 5, 6, 7]

结论：

　　yield和yield from后边加上可迭代对象的时候，yield from是将可迭代对象中的元素一个一个yield出来，而yield是直接yield的是可迭代对象