引号的问题（红宝石）

Question

任何想法我怎么能传递正确的参数的XPath？必须有一些关于如何使用单/双引号。当我使用变量

parser_xpath_identificator = "'//table/tbody[@id=\"threadbits_forum_251\"]/tr'"给我一个不正确的值或

parser_xpath_identificator = "'//table/tbody[@id="threadbits_forum_251"]/tr'"给我一个错误的语法错误，意想不到的tIDENTIFIER，预计年底$ 的

require 'rubygems'
require 'mechanize'

parser_xpath_identificator = "'//table/tbody[@id=\"threadbits_forum_251\"]/tr'"
#   parser_xpath_identificator = "'//table/tbody[@id="threadbits_forum_251"]/tr'"
    #gives an error: syntax error, unexpected tIDENTIFIER, expecting $end

agent = WWW::Mechanize.new
page = agent.get("http://www.vbulletin.org/forum/index.php")
page = page.link_with(:text=>'vB4 General Discussions').click
puts "Page title: #{page.title}"
puts "\nfrom variable: #{page.parser.xpath(parser_xpath_identificator).length}"
puts "directly: #{page.parser.xpath('//table/tbody[@id="threadbits_forum_251"]/tr').length}"

Answer 1

在这两种情况下，你是嵌套单引号里面直接双引号，我不认为这是正确的。尝试这样：

parser_xpath_identificator = '//table/tbody[@id="threadbits_forum_251"]/tr'