在Rails项目中要求'open-uri'是否安全？

Question

我已经看过很多open-uri的例子,对于简单的事情看起来非常棒.但是,要求它定义一个open在全局范围内命名的方法,这让我感到困扰.

这是特别令人不安的,因为在Rails 5控制台中探索后,似乎已经open定义了一个名为的方法:

irb(main):001:0> open
ArgumentError: wrong number of arguments (given 0, expected 1..3)
        from (irb):1:in `initialize'
        from (irb):1:in `open'
        from (irb):1
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/console.rb:65:in `start'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/console_helper.rb:9:in `start'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/commands_tasks.rb:78:in `console'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/command.rb:20:in `run'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands.rb:18:in `<top (required)>'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:302:in `require'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:302:in `block in require'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:268:in `load_dependency'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:302:in `require'
        from /Users/ahamon/code/signist/bin/rails:9:in `<top (required)>'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:296:in `load'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:296:in `block in load'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:268:in `load_dependency'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:296:in `load'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/commands/rails.rb:6:in `call'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/command_wrapper.rb:38:in `call'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:185:in `block in serve'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:156:in `fork'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:156:in `serve'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:131:in `block in run'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:125:in `loop'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:125:in `run'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application/boot.rb:18:in `<top (required)>'
        from /Users/ahamon/.rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /Users/ahamon/.rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from -e:1:in `<main>'irb(main):002:0>

如果我继续前进require 'open-uri',返回值是true,我现在已经删除了之前的open任何内容,无论它是什么:

irb(main):002:0> require 'open-uri'
=> true
irb(main):003:0> open
ArgumentError: wrong number of arguments (given 0, expected 1+)
        from /Users/ahamon/.rubies/ruby-2.3.0/lib/ruby/2.3.0/open-uri.rb:29:in `open'
        from (irb):3
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/console.rb:65:in `start'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/console_helper.rb:9:in `start'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/commands_tasks.rb:78:in `console'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/command.rb:20:in `run'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/railties-5.0.0.beta3/lib/rails/commands.rb:18:in `<top (required)>'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:302:in `require'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:302:in `block in require'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:268:in `load_dependency'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:302:in `require'
        from /Users/ahamon/code/signist/bin/rails:9:in `<top (required)>'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:296:in `load'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:296:in `block in load'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:268:in `load_dependency'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/activesupport-5.0.0.beta3/lib/active_support/dependencies.rb:296:in `load'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/commands/rails.rb:6:in `call'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/command_wrapper.rb:38:in `call'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:185:in `block in serve'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:156:in `fork'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:156:in `serve'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:131:in `block in run'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:125:in `loop'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application.rb:125:in `run'
        from /Users/ahamon/.gem/ruby/2.3.0/gems/spring-1.6.4/lib/spring/application/boot.rb:18:in `<top (required)>'
        from /Users/ahamon/.rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /Users/ahamon/.rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from -e:1:in `<main>'irb(main):004:0>

注意每个堆栈跟踪中指定的不同arity.

那么open之前定义的是什么？擦除是否安全？有没有办法在不定义全局方法的情况下使用open-uri？

Answer 1

open是Kernel#open,不是Rails.open-uri换行Kernel#open:它检查目标是否是URL或知道#open,如果是,则处理它,如果不是,则将所有内容传递给实际Kernel#open.

因此,如果没有open-uri,URL不起作用,openables不起作用,其他一切都不起作用.随着open-uriURL工作,openable工作,其他一切都是一样的.在open-uri检查您的参数是URL还是响应时,除了非常非常轻微的性能损失之外,应该没有危险#open.