Error: undefined method `cask' for main:Object

[hamiltop]

When I run brew cask install elm-platform (or any package) I get:

Error: undefined method `cask' for main:Object
Please report this bug:
    https://github.com/caskroom/homebrew-cask/issues
/usr/local/Library/Taps/caskroom/homebrew-cask/Casks/haskell-platform.rb:1:in `<top (required)>'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/source/path_base.rb:22:in `load'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/source/tapped.rb:28:in `load'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask.rb:120:in `load'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/cli/install.rb:19:in `block in install_casks'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/cli/install.rb:17:in `each'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/cli/install.rb:17:in `install_casks'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/cli/install.rb:6:in `run'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/cli.rb:80:in `run_command'
/usr/local/Cellar/brew-cask/0.37.1/rubylib/cask/cli.rb:120:in `process'
/usr/local/bin/brew-cask.rb:42:in `<top (required)>'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
/usr/local/Library/brew.rb:59:in `require?'
/usr/local/Library/brew.rb:142:in `<main>'

[hamiltop]

brew upgrade caskroom/cask/brew-cask fixed it. Perhaps a better error message saying to try upgrading brew-cask would be good?

[rolandwalker]

Hi!

Yes, we try to generate those nice upgrade messages. In this case, the header line format had changed, and there was no way to catch the exception.

With that in mind, we cut forward-compatibility code 28 Jul 2014 (v0.38.0), deferred the header switchover until 13 Nov 2014 (#7315), and kept a banner on README.md until today (#7698).

That's not to dismiss your bug report – the real-world data point is helpful and appreciated. We apologize for the inconvenience, and will keep trying to manage transitions to new features as smoothly we can (#4688).