CoffeeScript 类扩展 - TypeError: Object #没有“执行”方法；

Question

class Search
  perform: (text) ->
    query = encodeURIComponent text
    results = ''
    request {uri: @uri + query }, (error, response, body) =>
      if !error? && response.statusCode == 200
        window = jsdom.jsdom(body).createWindow()
        jsdom.jQueryify window, './jquery-1.5.min.js', (window, jquery) =>
          $ = window.$
          jquery(@pattern).each (i, lmn) =>
            link = $(lmn).text() + " - " +  $(lmn).attr('href') 
            if requiresHttp? && /^http/.exec  $(lmn).attr('href')
              results = results + link + "\n"
            else
              results = results + link + "\n"
          @emit 'end', results

sys.inherits(Search, process.EventEmitter)

class Google extends Search
  @uri     = 'http://www.google.com/search?q='
  @pattern = '#ires ol li .r a'

当我执行时，

google = new Google
google.perform 'blah'

它返回错误“TypeError: Object #Google has no method 'perform'”。扩展不应该提供该方法吗？

更新

发布后不久，我重构了代码。这是工作结果：

{EventEmitter} = require "events"
request        = require 'request'
jsdom          = require 'jsdom'


class Search extends EventEmitter
  constructor: ->
    @linkPrefix   = ''
    @requiresHttp = false
    @uri          = ''
    @pattern      = ''
  perform: (text) ->
    query = encodeURIComponent text
    results = ''
    request {uri: @uri + query }, (error, response, body) =>
      if !error? && response.statusCode == 200
        window = jsdom.jsdom(body).createWindow()
        jsdom.jQueryify window, './jquery-1.5.min.js', (window, jquery) =>
          $ = window.$
          jquery(@pattern).each (i, lmn) =>
            link = $(lmn).text() + " - " + @linkPrefix + $(lmn).attr('href') 
            if @requiresHttp?
              if /^http/.exec  $(lmn).attr('href')
                results = results + link + "\n"
            else
              results = results + link + "\n"
          @emit 'end', results

class Google extends Search
  constructor: ->
    @uri          = 'http://www.google.com/search?q='
    @pattern      = '#ires ol li .r a'
    @requiresHttp = true

class Youtube extends Search
  constructor: ->
    @uri          = 'http://www.youtube.com/results?search_query='
    @pattern      = '#search-results h3 a'
    @linkPrefix   = 'http://www.youtube.com'


exports.Google  = Google
exports.Youtube = Youtube

Answer 1

CD Sandchez 的评论是正确的。如果删除 sys.inherits 行，则 perform 运行。

你应该做的是一直使用 CoffeeScript 继承：

class Search extends process.EventEmitter