python下载安装教程(python中eval()函数的作用是什么?)

今天遇见一个很奇怪的问题，使用tornado搭建服务器，第一次我是这样写的

self.render('index.html',name = "name")

在页面{{name}}可以正常取值,随后又加了几个参数就开始报错

import os

import tornado.web
import tornado.ioloop
import tornado.options

tornado.options.parse_command_line()


class IndexHandler(tornado.web.RequestHandler):
    def get(self,*args, **kwargs):
        self.write('hello tornado') # write()执行后会将内容增加到缓冲区，手动finish()时才会将内容响应
        self.render('index.html',name='name',clist=['2','3','4'],mdict={'k':'v'})

if __name__ == "__main__":
    settings = {
        "template_path": os.path.join(os.path.dirname(__file__), "templates"),
        "debug": True
    }
    app = tornado.web.Application(
        [
            (r"^/index$", IndexHandler),
        ],**settings
    )
    httpServer = tornado.httpserver.HTTPServer(app)
    httpServer.bind(8000) 
    httpServer.start(1) 
    tornado.ioloop.IOLoop.current().start()

# 错误信息如下
[E 220320 14:17:09 web:1670] Uncaught exception GET /index (127.0.0.1)
    HTTPServerRequest(protocol='http', host='127.0.0.1:8000', method='GET', uri='/index', version='HTTP/1.1', remote_ip='127.0.0.1')
    Traceback (most recent call last):
      File "D:py_virtual_envfuyiTornadolibsite-packagestornadoweb.py", line 1590, in _execute
        result = method(*self.path_args, **self.path_kwargs)
      File "D:/project/PPY/pycharmProjects/tornado_day/test1/quantao/server.py", line 18, in get
        self.render('index.html',uname='zhangsan',clist=['2','3','4'],mdict={'k':'v'})
      File "D:py_virtual_envfuyiTornadolibsite-packagestornadoweb.py", line 766, in render
        html = self.render_string(template_name, **kwargs)
      File "D:py_virtual_envfuyiTornadolibsite-packagestornadoweb.py", line 907, in render_string
        return t.generate(**namespace)
      File "D:py_virtual_envfuyiTornadolibsite-packagestornadotemplate.py", line 346, in generate
        return execute()
      File "index_html.generated.py", line 5, in _tt_execute
        _tt_tmp = name  # index.html:8
    NameError: name 'name' is not defined
[E 220320 14:17:09 web:2162] 500 GET /index (127.0.0.1) 9.00ms
[I 220320 14:17:53 autoreload:199] D:/project/PPY/pycharmProjects/tornado_day/test1/quantao/server.py modified; restarting server

折腾了半天，终于发现问题了
原来是html页面这里的注释没有用，需要吧这些取值删掉才行。