Guard不会加载WDM

Question

I'm working through Michael Hartl's Rails tutorial which is excellent so far. I'm on the Advanced Setup Chapter, where he goes through configuring the Rails environment in a way conducive to TDD. I installed Guard, and it runs properly all the way through running the tests I have in my spec/ folder. But then, it spits out this error:

C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/listen-1.0.2/lib/listen/adapter.rb:195:in `require': cannot load such file -- wdm (LoadError)

I have wdm installed. I don't know why it can't load it.

It seems like Listen is having problems loading up WDM. It quits after it says "Guard is now watching..."

I haven't reproduced the rest of the stack trace for obvious reasons. I installed Rails using the latest Rails Installer. What's going on here? Do I need to worry about this? It appears to work at least partially...

Answer 1

So here's what happened. By default, on Windows, Listen is supposed to use polling to check for filesystem changes. For some reason it was trying to use WDM. So, I had to had this to my Gemfile:

require 'rbconfig'
gem 'wdm', '>= 0.1.0' if RbConfig::CONFIG['target_os'] =~ /mswin|mingw/i

Maybe Guard makes Listen try to use WDM?

Answer 2

Can't find where I got this recommendation from, but I was given the following for running guard across windows and linux:

gem 'rb-inotify', github: 'nex3/rb-inotify', platforms: :ruby, require: false
gem 'wdm', platforms: :mingw, require: false

The false's make it so the gems are only attempted to be loaded when running on that platform. Your windows environment may need mswin instead of mingw , depending on which ruby install you're using.

Answer 3

Like said Binary Phile If you use rails in both windows and unix-like, you should use this in your Gemfile :

gem 'wdm','>= 0.1.0', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

it works fine and it's readable.