I have several classes (Elves, Dwarves, Giants, etc.), and I would like to add "powers" to them via a powerable module that lets me add several fields/methods to a model (I am using Mongoid just for the sake of example) using a simple DSL has_superpower(power_name)
module Powerable::Elf
extend ActiveSupport::Concern
include Powerable::Mongoid
has_superpower(:super_hearing)
has_superpower(:night_vision)
end
class Elf
include Powerable::Elf
end
Each time I call the class method has_superpower(power_name), it should register the power_name somewhere so I can later get the list of all added powers on a class (and reflect on those names to call other methods).
I don't know how to do that. I had a look at class instance variables or class variables but I'm not sure how to use them for this context
Consider the following boilerplate
module Powerable
module Mongoid
extend ActiveSupport::Concern
def use_power!(power_name, options = {})
send(:"last_#{power_name}_used_at=", Time.now)
...
# Log the power use to the :#{power_name}_uses array
push(#{power_name}_uses, power: power_name, time: Time.now, **options)
end
class_methods do
def has_superpower(power_name)
field :"last_#{power_name}_used_at", type: DateTime
field :"last_#{power_name}_count", type: Integer
field :"#{power_name}_uses", type: Array
end
end
end
Now I would like to define a method that gives me all the uses of all superpowers. For this I would need to register the powers one has, so I can resolve the model fields I need to look at
# I am adding the following to the above module Powerable::Mongoid
module Powerable
module Mongoid
def power_uses(power_name = nil)
if power_name.blank? # Retrieve all power uses)
self.class.all_powers.flat_map do |power_name|# đź‘€ I do not know how to code all_powers
send(:"#{power_name}_uses")
end
else
send(:"#{power_name}_uses")
end
end
end
end
The idea
elf = Elf.new
elf.use_power!(:night_vision, moon: :crescent)
elf.use_power!(:super_hearing, distance: 1.kilometer)
elf.power_uses # => [
power: night_vision, time: xxx, moon: :crescent,
power: super_hearing, time: xxx, distance: 1.kilometer
]
Related
It seems I don't quite understand initializing or using a class within another class.
I have a Sinatra app and have created a class to handle fetching data from an api
# path: ./lib/api/bikes/bike_check
class BikeCheck
def self.check_frame_number(argument)
# logic here
end
end
BikeCheck.new
I then have another class that needs to consume/use the check_frame_number method
require 'slack-ruby-bot'
# Class that calls BikeCheck api
require './lib/api/bikes/bike_check'
class BikeCommands < SlackRubyBot::Bot
match /^Is this bike stolen (?<frame_number>\w*)\?$/ do |client, data, match|
check_frame_number(match[:frame_number])
client.say(channel: data.channel, text: #message)
end
end
BikeCommands.run
When check_frame_number is called I get a undefined method error. What I would like to know is what basic thing am I not doing/understanding, I thought by requiring the file which has the class it would be available to use.
No, you can not require a method defined in class - methods defined in class only available to class, class instances and within the inheritance.
Mixing method only possible with including modules.
To solve you issue you could either do
class BikeCommands < SlackRubyBot::Bot
match /^Is this bike stolen (?<frame_number>\w*)\?$/ do |client, data, match|
BikeCheck.check_frame_number(match[:frame_number]) # <===========
client.say(channel: data.channel, text: #message)
end
end
or write a module with the method and include/extend in class, you want that method to be available in.
I am working on creating a generator similar to the Rails scaffolding generator. I would like to accept an array of key:value arguments. Like this:
mycli generate model BlogPost title:string body:text published:datetime
Currently my command class looks something like this:
require "thor"
module Mycli
module Generators
class Model < Thor::Group
include Thor::Actions
argument :model_name
# argument :model_attributes # TODO: figure out how to get array of attributes
def self.source_root
File.dirname(__FILE__)
end
def generate_model
template('templates/model.tt', "app/models/#{model_name}.rb")
end
def generate_migration
template('templates/migration.tt', "migrations/#{model_name}.rb")
end
end
end
end
What do I need to do in order to access that list of attributes?
Looks like this feature is already supported. You just need to specify the argument type as a :hash.
argument :model_attributes, optional: true, type: :hash
I am trying to understand how the following code is able to do this:
attr_accessor *Configuration::VALID_CONFIG_KEYS
Without requiring the Configuration file. Here is part of the code:
require 'openamplify/analysis/context'
require 'openamplify/connection'
require 'openamplify/request'
module OpenAmplify
# Provides access to the OpenAmplify API http://portaltnx20.openamplify.com/AmplifyWeb_v20/
#
# Basic usage of the library is to call supported methods via the Client class.
#
# text = "After getting the MX1000 laser mouse and the Z-5500 speakers i fell in love with logitech"
# OpenAmplify::Client.new.amplify(text)
class Client
include OpenAmplify::Connection
include OpenAmplify::Request
attr_accessor *Configuration::VALID_CONFIG_KEYS
def initialize(options={})
merged_options = OpenAmplify.options.merge(options)
Configuration::VALID_CONFIG_KEYS.each do |key|
send("#{key}=", merged_options[key])
end
end
....
end
And this is the Configuration module:
require 'openamplify/version'
# TODO: output_format, analysis, scoring can be specied in the client and becomes the default unless overriden
module OpenAmplify
# Defines constants and methods for configuring a client
module Configuration
VALID_CONNECTION_KEYS = [:endpoint, :user_agent, :method, :adapter].freeze
VALID_OPTIONS_KEYS = [:api_key, :analysis, :output_format, :scoring].freeze
VALID_CONFIG_KEYS = VALID_CONNECTION_KEYS + VALID_OPTIONS_KEYS
DEFAULT_ENDPOINT = 'http://portaltnx20.openamplify.com/AmplifyWeb_v21/AmplifyThis'
DEFAULT_HTTP_METHOD = :get
DEFAULT_HTTP_ADAPTER = :net_http
DEFAULT_USER_AGENT = "OpenAmplify Ruby Gem #{OpenAmplify::VERSION}".freeze
DEFAULT_API_KEY = nil
DEFAULT_ANALYSIS = :all
DEFAULT_OUTPUT_FORMAT = :xml
DEFAULT_SCORING = :standard
DEFAULT_SOURCE_URL = nil
DEFAULT_INPUT_TEXT = nil
attr_accessor *VALID_CONFIG_KEYS
....
end
This is from this repository: OpenAmplify
First of all, in both configuration.rb and client.rb, they're using the same naming space, which is module OpenAmplify.
Even though configuration.rb is not required in client.rb, the convention of Ruby project usually requires all necessary files in one file (normally the same name as the name space, and placed in {ProjectName}/lib/, in this case the file is openamplify/lib/openamplify.rb).
So if you go to openamplify/lib/openamplify.rb, you'll notice it actually requires all those two files:
require 'openamplify/configuration'
require 'openamplify/client'
And since constants are already defined in configuration.rb:
module OpenAmplify
module Configuration
VALID_CONFIG_KEYS = ...
end
end
Then obviously constant VALID_CONFIG_KEYS is visible in the same module (re-opened by client.rb) by Configuration::VALID_CONFIG_KEYS (and the * in front just means exploding array, because VALID_CONFIG_KEYS is an array of symbols)
module OpenAmplify
class Client
attr_accessor *Configuration::VALID_CONFIG_KEYS
end
end
I'm using data_mapper/sinatra and trying to create some attributes with attr_accessor. The following example code:
require 'json'
class Person
include DataMapper::Resource
property :id, Serial
property :first_name, String
attr_accessor :last_name
end
ps = Person.new
ps.first_name = "Mike"
ps.last_name = "Smith"
p ps.to_json
produces this output:
"{\"id\":null,\"first_name\":\"Mike\"}"
Obviously I would like for it to give me both the first and last name attributes. Any ideas on how to get this to work in the way one would expect so that my json has all of the attributes?
Also, feel free to also explain why my expectation (that I'd get all of the attributes) is incorrect. I'm guessing some internal list of attributes isn't getting the attr_accessor instance variables added to it or something. But even so, why?
Datamapper has it’s own serialization library, dm-serializer, that provides a to_json method for any Datamapper resource. If you require Datamapper with require 'data_mapper' in your code, you are using the data_mapper meta-gem that requires dm-serializer as part of it’s set up.
The to_json method provided by dm-serializer only serializes the Datamapper properties of your object (i.e. those you’ve specified with property) and not the “normal” properties (that you’ve defined with attr_accessor). This is why you get id and first_name but not last_name.
In order to avoid using dm-serializer you need to explicitly require those libraries you need, rather than rely on data_mapper. You will need at least dm-core and maybe others.
The “normal” json library doesn’t include any attributes in the default to_json call on an object, it just uses the objects to_s method. So in this case, if you replace require 'data_mapper' with require 'dm-core', you will get something like "\"#<Person:0x000001013a0320>\"".
To create json representations of your own objects you need to create your own to_json method. A simple example would be to just hard code the attributes you want in the json:
def to_json
{:id => id, :first_name => first_name, :last_name => last_name}.to_json
end
You could create a method that looks at the attributes and properties of the object and create the appropriate json from that instead of hardcoding them this way.
Note that if you create your own to_json method you could still call require 'data_mapper', your to_json will replace the one provided by dm-serializer. In fact dm-serializer also adds an as_json method that you could use to create the combined to_json method, e.g.:
def to_json
as_json.merge({:last_name => last_name}).to_json
end
Thanks to Matt I did some digging and found the :method param for dm-serializer's to_json method. Their to_json method was pretty decent and was basically just a wrapper for an as_json helper method so I overwrote it by just adding a few lines:
if options[:include_attributes]
options[:methods] = [] if options[:methods].nil?
options[:methods].concat(model.attributes).uniq!
end
The completed method override looks like:
module DataMapper
module Serializer
def to_json(*args)
options = args.first
options = {} unless options.kind_of?(Hash)
if options[:include_attributes]
options[:methods] = [] if options[:methods].nil?
options[:methods].concat(model.attributes).uniq!
end
result = as_json(options)
# default to making JSON
if options.fetch(:to_json, true)
MultiJson.dump(result)
else
result
end
end
end
end
This works along with an attributes method I added to a base module I use with my models. The relevant section is below:
module Base
def self.included(base)
base.extend(ClassMethods)
end
module ClassMethods
def attr_accessor(*vars)
#attributes ||= []
#attributes.concat vars
super(*vars)
end
def attributes
#attributes || []
end
end
def attributes
self.class.attributes
end
end
now my original example:
require 'json'
class Person
include DataMapper::Resource
include Base
property :id, Serial
property :first_name, String
attr_accessor :last_name
end
ps = Person.new
ps.first_name = "Mike"
ps.last_name = "Smith"
p ps.to_json :include_attributes => true
Works as expected, with the new option parameter.
What I could have done to selectively get the attributes I wanted without having to do the extra work was to just pass the attribute names into the :methods param.
p ps.to_json :methods => [:last_name]
Or, since I already had my Base class:
p ps.to_json :methods => Person.attributes
Now I just need to figure out how I want to support collections.
Also, what does "self.send attr" do? Is attr assumed to be a private instance variable of the ActiveEngineer class? Are there any other issues with this code in terms of Ruby logic?
class Applicant < ActiveEngineer
require 'ruby'
require 'mad_skills'
require 'oo_design'
require 'mysql'
validates :bachelors_degree
def qualified?
[:smart, :highly_productive, :curious, :driven, :team_player ].all? do
|attr|
self.send attr
end
end
end
class Employer
include TopTalent
has_millions :subscribers, :include=>:mostly_women
has_many :profits, :revenue
has_many :recent_press, :through=>[:today_show, :good_morning_america,
:new_york_times, :oprah_magazine]
belongs_to :south_park_sf
has_many :employees, :limit=>10
def apply(you)
unless you.build_successful_startups
raise "Not wanted"
end
unless you.enjoy_working_at_scale
raise "Don't bother"
end
end
def work
with small_team do
our_offerings.extend you
subscribers.send :thrill
[:scaling, :recommendation_engines, : ].each do |challenge|
assert intellectual_challenges.include? challenge
end
%w(analytics ui collaborative_filtering scraping).each{|task|
task.build }
end
end
end
def to_apply
include CoverLetter
include Resume
end
require 'mad_skills' loads the code in mad_skills.rb (or it loads mad_skills.so/.dll depending on which one exists). You need to require a file before being able to use classes, methods etc. defined in that file (though in rails files are automatically loaded when trying to access classes that have the same name as the file). Putting require inside a class definition, does not change its behaviour at all (i.e. putting it at the top of the file would not make a difference).
include MadSkills takes the module MadSkills and includes it into Applicant's inheritance chain, i.e. it makes all the methods in MadSkills available to instances of Applicant.
self.send attr executes the method with the name specified in attr on self and returns its return value. E.g. attr = "hello"; self.send(attr) will be the same as self.hello. In this case it executes the methods smart, highly_productive, curious, driven, and team_player and checks that all of them return true.