Question

我练习Scrapy并且想问一个问题：

我知道如何在课外使用def printTW 我在课堂上写的时候如何调用呢？我的代码在这里：请教我

from scrapy.spider import Spider
from scrapy.selector import Selector
from yahoo.items import YahooItem

def printTW(original_line):
    for words in original_line:
        print words.encode('utf-8')     

class MySpider(Spider):   
    name = "yahoogo"
    start_urls = ["https://tw.movies.yahoo.com/chart.html"]  

    #Don't know how to calling this
    #def printTW(original_line):
    #    for words in original_line:
    #        print words.encode('utf-8')     

    def parse(self, response):
        for sel in response.xpath("//tr"):
            movie_description = sel.xpath("td[@class='c3']/a/text()").extract()
            printTW(movie_description)

Answer 1

要调用实例方法，您需要使用self限定方法。

self.printTW(movie_description)

该方法应该有self作为第一个参数：

def printTW(self, original_line):
    for words in original_line:
        print words.encode('utf-8')

因为printTW不使用任何实例属性，所以可以将方法定义为静态方法（或者可以将其定义为函数，而不是方法）。

@staticmethod
def printTW(original_line):
    for words in original_line:
        print words.encode('utf-8')

Answer 2

将函数声明为您希望调用它的方法中的全局函数，如下所示：

def parse(self, response):
    global printTW
    for sel in response.xpath("//tr"):
        movie_description = sel.xpath("td[@class='c3']/a/text()").extract()
        printTW(movie_description)

Python：如何在课堂上调用def

2 个答案: