Добрин обнови решението на 25.11.2016 18:50 (преди около 8 години)
+module SubHashChecker
+ def sub_hash?(main_hash, sub_hash)
+ sub_hash.each do |key, value|
Има по-подходящи методи тук. Не пиши на C
+ return false if main_hash[key] != value
+ end
+ true
+ end
+end
+
+module DataModelSingletonMethods
+ def data_store(repository = nil)
+ if repository
+ instance_variable_set(:@repository, repository)
Не. Виж пак лекциите. Имаш достъп до тези променливи тук директно. Защо го правиш толкова заобиколно?
+ else
+ instance_variable_get(:@repository)
+ end
+ end
+
+ def attributes(*attribute_names)
+ if attribute_names.empty?
+ instance_variable_get(:@attribute_names)
+ else
+ instance_variable_set(:@attribute_names, attribute_names)
+ @attribute_names << :id
+ end
+ @attribute_names.each { |attribute| attr_accessor attribute }
+ end
+
+ def where(criteria)
+ check_for_invalid_keys(criteria, @attribute_names)
+ result = []
+ ObjectSpace.each_object(self) do |x|
Не не не не не не не не. Не.
Затова ти е data store-а. В него искаш да съхраняваш неща.
Но в data store-a имам само хешове, а не конкретни инстанции на модел. Нали where трябва да връща инстанции?! Тогава да обходя data store и за всеки хеш, който изпълнява критерийте да създам нова инстанция ли?
Да. DataStore-а ти е като файл. Във файл няма как да имаш инстанция на клас - имаш някаква структурирана информация (например, json).
В условието пише Задача на самия модел е да преобразува инстанции от и към хешове преди да ги подаде на/вземе от съответния store.
+ predicate1 = x.instance_variable_get(:@saved_to_repository)
+ predicate2 = sub_hash?(x.hash_information, criteria)
+ result << x if predicate1 && predicate2
+ end
+ result
+ end
+end
+
+module InitializeHelpers
+ def initialize_attributes(names, information_hash)
+ names.each do |attribute|
+ value = information_hash[attribute]
+ if value
+ send("#{attribute}=".to_sym, value)
+ else
+ send("#{attribute}=".to_sym, nil)
+ end
+ end
+ end
+
+ def initialize_singleton_finders(names, which_class)
+ names.each do |attribute|
+ which_class.define_singleton_method "find_by_#{attribute}".to_sym do |value|
+ hash_attribute = {attribute => value}
+ which_class.where(hash_attribute)
+ end
+ end
+ end
+end
+
+module Helpers
+ include SubHashChecker
+ include InitializeHelpers
+
+ def check_for_invalid_keys(criteria_hash, attribute_names)
+ criteria_hash.each do |key, _|
+ unless attribute_names.include?(key)
+ raise DataModel::UnknownAttributeError, "Unknown attribute #{key}"
+ end
+ end
+ end
+
+ def find_id_for_instance(instance, repository)
+ @id = 1
+ @id += 1 while repository.find({id: @id}) != []
+ instance[:id] = @id
+ repository.create(instance)
+ @saved_to_repository = true
+ end
+end
+
+class HashStore
+ include Helpers
+ attr_reader :storage
+ def initialize
+ @storage = {}
+ end
+
+ def create(information_hash)
+ id = information_hash[:id]
+ @storage[id] = information_hash
+ end
+
+ def find(search_hash)
+ result = []
+ @storage.each do |_, current_hash|
+ result << current_hash if sub_hash?(current_hash, search_hash)
+ end
+ result
+ end
+
+ def update(id, to_overload)
+ desired_hash = storage[id]
+ to_overload.each do |key, value|
+ desired_hash[key] = value
+ end
+ end
+
+ def delete(search_hash)
+ matches = find(search_hash)
+ matches.each do |current_hash|
+ id = current_hash[:id]
+ @storage.delete(id)
+ end
+ end
+end
+
+class ArrayStore
+ include Helpers
+ attr_reader :storage
+ def initialize
+ @storage = []
+ end
+
+ def create(information_hash)
+ @storage << information_hash
+ end
+
+ def find(search_hash)
+ result = []
+ @storage.each do |current_hash|
+ result << current_hash if sub_hash?(current_hash, search_hash)
+ end
+ result
+ end
+
+ def update(id, to_overload)
+ desired_hash = storage[id]
+ storage.each do |current_hash|
+ if current_hash[:id] == id
+ desired_hash = current_hash
+ break
+ end
+ end
+ to_overload.each do |key, value|
+ desired_hash[key] = value
+ end
+ end
+
+ def delete(search_hash)
+ matches = find(search_hash)
+ matches.each do |current_hash|
+ @storage.delete(current_hash)
+ end
+ end
+end
+
+class DataModel
+ include Helpers
+ extend Helpers
+ extend DataModelSingletonMethods
+ class DeleteUnsavedRecordError < RuntimeError; end
+ class UnknownAttributeError < RuntimeError; end
+ attr_reader :saved_to_repository
+
+ def initialize(information_hash = {})
+ names = self.class.instance_variable_get(:@attribute_names)
+ initialize_attributes(names, information_hash)
+ @id = 1
+ @saved_to_repository = false
+ initialize_singleton_finders(names, self.class)
+ end
+
+ def hash_information
+ names = self.class.instance_variable_get(:@attribute_names)
+ result = {}
+ names.each do |attribute|
+ result[attribute] = send attribute
+ end
+ result.delete(:id)
+ result
+ end
+
+ def save
+ repository = self.class.instance_variable_get(:@repository)
+ instance = hash_information
+ if !@saved_to_repository
+ find_id_for_instance(instance, repository)
+ else
+ repository.update(repository.find(instance)[0][:id], instance)
+ end
+ self
+ end
+
+ def delete
+ repository = self.class.instance_variable_get(:@repository)
+ if repository.find(hash_information) == []
+ raise DeleteUnsavedRecordError
+ else
+ repository.delete(hash_information)
+ end
+ end
+
+ def ==(other)
+ return false unless other.instance_of?(self.class)
+ if @saved_to_repository && other.saved_to_repository && id == other.id
+ true
+ else
+ self.equal?(other)
+ end
+ end
+end
Направил си го милион пъти по-сложно, отколкото трябва. Като страничен ефект, няма да работи правилно.
Изчети пак лекциите за модулите и не наблягай толкова на метапрограмирането.