Flat Hash¶ ↑

Serialisation for hash instances.

It’s a bit of a struggle to justify creating this gem. It just encapsulates some functionality that i’d built twice in other gems (shh and cardigan). In both cases, I wanted to be able to manage a collection of serialised hash instances on all platforms in a version control system. I’d used yaml initially but found that serialising the same hash on windows vs linux would produced slight differences.

It serialises hashes that must contain only string keys and string values. It serialises to a human readable text file. The key must not contain a new line.

This class is just used to read and write hashes from disk

Reading:

File.open 'hash' do |in_io|
  hash = FlatHash::Serialiser.new.read File.open('hash)
end

Writing:

File.open 'hash', 'w' do |out_io|
  FlatHash::Serialiser.new.write out_io, hash
end

This enables a collection of hashes to be managed in a directory (a pseudo database table). If the directory does not exist, it will be created with the first write.

serialiser = FlatHash::Serialiser.new 
directory = FlatHash::Directory serialiser, 'classes'
directory['cs101'] = {'name', 'computer science 101', 'lecturer': 'alan turing'}
directory['el101'] = {'name', 'english literature 101', 'lecturer': 'marcel proust'}
directory.each {|subject| p subject}

This is a FlatHash::Directory with some additional vcs capabilities. It will detect whether the directory is in a git or mercurial repository. If a vcs is detected, it is possible to traverse the history for each hash.

serialiser = FlatHash::Serialiser.new 
repository = FlatHash::Repository serialiser, 'classes'
repository.history('el101').each do |changeset|
  p repository.element_at changeset.id, 'el101'
end