Change

What files changed since last time?

gem install change

@change = Change.new("/absolute/path")
@change.d?("relative/path")
@change.d        # { :add => [], :mod => [], :rem => [] }
@change.d(true)  # reload

Change uses a YAML file stored in the root directory called .change.yml to maintain state.

Calling @change.d? does the following:

• Check if there is an entry for path in .change.yml
  • If yes, read file size and compare with entry
    • If file size matches, compare hash
  • If no, record file size and hash
• Look up path in dependency tree
  • If found, also mark all dependency parent paths as changed

To group dependencies, Change uses the concept of a "session":

@change = Change.new("/absolute/path")
@change.s(:some_id)         # start session with id
@change.r("relative/path")  # record dependency
@change.s(nil)              # stop session

If you use @change.d? within a session, it will return true if any dependencies have changed. Change recalls the dependencies from the last session to achieve this.

@change.s(:some_id)
@change.d?('relative/path')
  # returns true if any dependencies have changed
  # dependencies are recalled from LAST :some_id session

Recall files that were modified during the last execution of this session:

@change.s(:some_id)
@change.d_  # returns: { :add => [], :mod => [], :rem => [] }