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require 'ffi'

# Example 1: libc - puts

module MyLib
  extend FFI::Library
  ffi_lib 'c'
  attach_function :puts, [ :string ], :int
end

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require 'dry-validation'

schema = Dry::Validation.Schema do
  required(:name).filled
  required(:age).maybe(:int?)
  optional(:sex).value( included_in?: %w(M F) )
end

hash = { name: 'Jane', email: '[email protected]' }
hash[:age] = 21

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# Set values in new block

class MyClass
  attr_accessor :name, :val
  def initialize
    yield self if block_given?
  end
end

MyClass.new do |obj|

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# Ruby offers different ways to extend classes / monkey patch / override methods.
# A good way to execute code before or after a method of a class is using prepend

class Test
  def fun
    puts 'Inside fun()'
  end
end

Test.new.fun

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# Rails - sometimes it's needed to execute some code before anything else but after Rails core is loaded. A good place to achieve this is using after_initialize in config/application.rb:

# ... config requires ...
module MyApp
  class Application < Rails::Application
    config.after_initialize do
      # init code here...
    end
  end
end

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• Load rails app from irb: require_relative 'config/environment.rb' (after that Rails.application is available)
• Translation key for a model (ex. MyModel): MyModel.model_name.i18n_key
• Clean and recompile assets: rake assets:clean assets:clobber assets:precompile (preperate RAILS_ENV=production to set env)
• Enable/disable cache in development: rake dev:cache
• Dev routes: /rails/info/properties - /rails/info/routes
• Search for notes comments ([TODO], [FIXME], etc.): rake notes
• Dump/restore DB structure: rake db:structure:dump - rake db:structure:load
• Funny method: ActionDispatch::IntegrationTest.i_suck_and_my_tests_are_order_dependent!

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# An implementation of static method chaining - like ActiveRecord, for example: Model.where( condition: true )

class Chain
  attr_accessor :ref, :val

  def initialize( ref, val = {} )
    @ref = ref
    @val = val
  end

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# Look for a specific string (optionally filtering files with a pattern) of my projects

require 'git'
require 'pathname'

BASE_PATH='/projects'
search='class_eval'
filter_files='*.rb' # Empty for every file

Pathname.new( BASE_PATH ).children.each do |path|

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• To ignore ActiveAdmin exceptions while migrating: update routes.rb: ActiveAdmin.routes(self) rescue ActiveAdmin::DatabaseHitDuringLoad

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# All specs in the diff commits from develop (useful to check a specific branch):
git diff-tree --no-commit-id --name-only -r develop..HEAD | grep '_spec\.rb' | sort | uniq > /tmp/specs

# All specs in a specific range of commits:
git diff-tree --no-commit-id --name-only -r HEAD~3..HEAD | grep '_spec\.rb' | sort | uniq > /tmp/specs

# Execute them:
while read p; do; if [ -f "$p" ]; then; be rspec "$p" || break; fi; done </tmp/specs