如何从ruby脚本中安装rubygem并在之后需要这个gem？

Posted 2021-04-15

我想做这样的事情：

begin
  require 'progressbar'
rescue LoadError => e
  puts "exception .. installing with gem"
  h = system 'gem install progressbar'
  puts "gem installed #{h}"
  require 'progressbar'
end
pbar = ProgressBar.new("test", 100)
100.times {sleep(0.1); pbar.inc}; pbar.finish

但很明显，如果您运行此代码段，则进度条宝石不可用。

答案

我发现了这个讨论：https://www.ruby-forum.com/topic/131346显然，调用Gem.clear_paths解决了这个问题。总共：

begin
  require 'progressbar'
rescue LoadError => e
  puts "exception .. installing gem"
  h = system 'gem install progressbar'
  puts "gem installed #{h}"
  Gem.clear_paths
  require 'progressbar'
end
pbar = ProgressBar.new("test", 100)
100.times {sleep(0.1); pbar.inc}; pbar.finish