python3 执行代码块,并返回数据 exec 返回值
Python3 exec 函数
描述
exec 执行储存在字符串或文件中的 Python 语句,相比于 eval,exec可以执行更复杂的 Python 代码。
语法
以下是 exec 的语法:
exec(object[, globals[, locals]])
参数
- object:必选参数,表示需要被指定的 Python 代码。它必须是字符串或 code 对象。如果 object 是一个字符串,该字符串会先被解析为一组 Python 语句,然后再执行(除非发生语法错误)。如果 object 是一个 code 对象,那么它只是被简单的执行。
- globals:可选参数,表示全局命名空间(存放全局变量),如果被提供,则必须是一个字典对象。
- locals:可选参数,表示当前局部命名空间(存放局部变量),如果被提供,可以是任何映射对象。如果该参数被忽略,那么它将会取与 globals 相同的值。
返回值
exec 返回值永远为 None。
exec 返回值永远为 None,那么如何返回结果呢?
直接上代码
# -*- coding: utf-8 -*- func_str = """ all_data = [ {'seed-url': 'https://rf.eefocus.com/', 'list-url': 'https://rf.eefocus.com/article/list-all/sort-new?p={}', 'pages': int(3)}, ] def generator(): url_list = [] for data in all_data: url = data['list-url'] pages = data['pages'] for page in range(1, int(pages)): url_list.append(url.format(page)) return url_list ab = generator() print("ab",ab) aa['ab'] = ab print("aa",aa) """ global aa aa = {} rees = exec(func_str) print("aa----",aa)
打印结果是:
C:\Python37\python3.exe D:/spider/spider_3_test.py ab ['https://rf.eefocus.com/article/list-all/sort-new?p=1', 'https://rf.eefocus.com/article/list-all/sort-new?p=2'] aa {'ab': ['https://rf.eefocus.com/article/list-all/sort-new?p=1', 'https://rf.eefocus.com/article/list-all/sort-new?p=2']} aa---- {'ab': ['https://rf.eefocus.com/article/list-all/sort-new?p=1', 'https://rf.eefocus.com/article/list-all/sort-new?p=2']} Process finished with exit code 0
方法二:直接上代码了
func_str = """ def generator(): all_data = [ {'seed-url': 'https://rf.eefocus.com/', 'list-url': 'https://rf.eefocus.com/article/list-all/sort-new?p={}', 'pages': int(3)}, ] url_list = [] for data in all_data: url = data['list-url'] pages = data['pages'] for page in range(1, int(pages)): url_list.append(url.format(page)) return url_list """ namespace = {} fun = compile(func_str,'<string>','exec') exec(fun,namespace) ret = namespace['generator']() print("ret",ret)
输出结果:
C:\Python37\python.exe D:/spider_2022/spider_11_jiagu/test.py
ret ['https://rf.eefocus.com/article/list-all/sort-new?p=1', 'https://rf.eefocus.com/article/list-all/sort-new?p=2']
Process finished with exit code 0
如果觉得对您有帮助,麻烦您点一下推荐,谢谢!
好记忆不如烂笔头
好记忆不如烂笔头