루비에서 재귀 메서드를 사용하는 방법

Question

나는 Mechanize를 사용하여 간단한 웹 스크롤러를 작성했습니다. 이제는 다음 페이지를 재귀 적으로 가져 오는 방법을 고수했습니다. 아래 코드를 참조하십시오.

def self.generate_page #generate a Mechainze page object,the first page 
    agent = Mechanize.new 
    url = "http://www.baidu.com/s?wd=intitle:#{URI.encode(WORD)}%20site:sina.com.cn&rn=50&gpc=stf#{URI.encode(TIME)}" 
    page = agent.get(url) 
    page 
end 

def self.next_page(n_page) #get next page recursively by click next tag showed in each pages 
puts n_page 
# if I dont use puts , I get nothing , when using puts, I get 
#<Mechanize::Page:0x007fd341c70fd0> 
#<Mechanize::Page:0x007fd342f2ce08> 
#<Mechanize::Page:0x007fd341d0cf70> 
#<Mechanize::Page:0x007fd3424ff5c0> 
#<Mechanize::Page:0x007fd341e1f660> 
#<Mechanize::Page:0x007fd3425ec618> 
#<Mechanize::Page:0x007fd3433f3e28> 
#<Mechanize::Page:0x007fd3433a2410> 
#<Mechanize::Page:0x007fd342446ca0> 
#<Mechanize::Page:0x007fd343462490> 
#<Mechanize::Page:0x007fd341c2fe18> 
#<Mechanize::Page:0x007fd342d18040> 
#<Mechanize::Page:0x007fd3432c76a8> 
#which are the results I want 

    np = Mechanize.new.click(n_page.link_with(:text=>/next/)) unless n_page.link_with(:text=>/next/).nil? 
    result = next_page(np) unless np.nil? 
    result # here the value is empty, I dont know what is worng 
end 

def self.get_page # trying to pass the result of next_page() method 
    puts next_page(generate_page) 
    # it seems result is never passed here, 
end 

나는 ... .. 뭐가 잘못 파악하지 못할 이러한 두 개의 링크 여전히 What is recursion and how does it work? 및 Ruby recursive function 하지만 따라 누군가가 나를 도울 수 있기를 바랍니다 감사합니다

Answer 1

코드와 몇 가지 문제가 있습니다

1. Mechanize.new 번을 두 번 이상 호출하면 안됩니다.
2. 문체 측면에서 볼 때 너무 많은 수표를 사용하고 있습니다.

재귀를 선호하지 않는 한 반복적으로 수행하는 것이 더 쉬울 것입니다. 당신의 next_page 방법은 체인의 모든 링크 페이지를 포함하는 배열을 반환해야하기

, 당신이 쓸 수 :

# you should store the mechanize agent as a global variable 
Agent = Mechanize.new 

# a helper method to DRY up the code 
def click_to_next_page(page) 
    Agent.click(n_page.link_with(:text=>/next/)) 
end 

# repeatedly visits next page until none exists 
# returns all seen pages as an array 
def get_all_next_pages(n_page) 
    results = [] 
    np = click_to_next_page(n_page) 
    results.push(np) 
    until !np 
    np = click_to_next_page(np) 
    np && results.push(np) 
    end 
    results 
end 

# testing it out (i'm not actually running this) 
base_url = "http://www.baidu.com/s?wd=intitle:#{URI.encode(WORD)}%20site:sina.com.cn&rn=50&gpc=stf#{URI.encode(TIME)}" 
root_page = Agent.get(base_url) 
next_pages = get_all_next_pages(root_page) 
puts next_pages