class Git::Object

def self.new(base, objectish, type = nil, is_tag = false)
  if is_tag
    sha = base.lib.tag_sha(objectish)
    if sha == ''
      raise Git::UnexpectedResultError.new("Tag '#{objectish}' does not exist.")
    end
    return Git::Object::Tag.new(base, sha, objectish)
  end
  type ||= base.lib.cat_file_type(objectish)
  klass =
    case type
    when /blob/   then Blob
    when /commit/ then Commit
    when /tree/   then Tree
    end
  klass.new(base, objectish)
end