Custom matchers in watches

Using custom matchers in watches

Intro

A watch statement filters files that changed to match the given regexp.

Since Guard 2.14.x, you can pass a custom matcher if it has the right methods.

This allows you to create powerful rules without complex and unreadable hacks.

Example

Lets say you want to respond only to changes in uncommitted files.

You might have:

only_uncommitted_lib_files = MyGitModifiedMatcher.new
watch(only_uncommitted_lib_files) { |m| "spec/#{m[:path_without_ext]}_spec.rb" }

A pseudo-implementation of the MySpecialMatcher class would be:

class MyGitModifiedMatcher
  class MyMatchData
    def initialize(result)
      @result = result
    end

    def to_a
      @result.values
    end

    def [](name)
      @result[name]
    end
  end

  def match(filename_or_pathname)
    return nil unless `git status -uno`.lines.map(&:chomp).include?(filename_or_pathname)
    MyMatchData.new(path_without_ext: File.basename(file,File.extname(file)))
  end
end

Feel free to open an issue to discuss improvements.