chapter1.md

Por qué preocuparse por la calidad de código?

1. Somos mejores programadores
2. Podemos reutilizar código
3. Generamos código más fácil de entender para los demas y para nosotros mismos
4. Somos más felices
5. Nos permite liberar código open source

Codigo bien estructurado VS código mal estructurado

Antes de empezar...

Tips para Javascript

Algo que todos debemos de saber del lenguaje es que tiene partes muy muy malas

  var a = '1'
  var b = 1

  a == b
  a === b

Module Pattern

El module pattern define una forma para definir modulos usando IIFE

Immediately-Invoked Function Expression

Son funciones que se mandan a llamar cuando se definen:

  #basic structure
  (function(){ /* code */ }());

  var SampleModule = (function(){
    'use strict';
    var my_fucking_private_function = function () {
      return 'private method';
    }

    var my_fucking_public_function = function () {
      return 'public method';
    }

    return
    {
      public_function: my_fucking_public_function
    }
   }());

#trying to call module function

![alt text](images/khe.png)

SampleModule.public_function()

Llaves a la derecha o a la izquierda?

  var return_json = function () {
    return
    {

    }
  }

Ahora sí deberia de funcionar :D

  #basic structure
  (function(){ /* code */ }());

  var SampleModule = (function(){
    'use strict';
    var my_fucking_private_function = function () {
      return 'private method';
    }

    var my_fucking_public_function = function () {
      return 'public method';
    }

    return
    {
      public_function: my_fucking_public_function
    }
   }());

#trying to call module function

SampleModule.public_function()

Principios de Codigo Limpio

DRY

Dont Repeat Yourself

Cuando lo usas? Siempre!

KISS

Keep It Simple, Stupid!

Cuando lo usas? Siempre!

En programación orientada a objetos

SOLID

Single Responsibility

A class should have only a single responsibility (i.e. only one potential change in the software's specification should be able to affect the specification of the class)

class DealProcessor
  def initialize(deals)
    @deals = deals
  end

  def process
    @deals.each do |deal|
      Commission.create(deal: deal, amount: calculate_commission)
      mark_deal_processed
    end
  end

  private

  def mark_deal_processed
    @deal.processed = true
    @deal.save!
  end

  def calculate_commission
    @deal.dollar_amount * 0.05
  end
end

Open-Closed

“software entities … should be open for extension, but closed for modification.”

class UsageFileParser
  def initialize(client, usage_file)
    @client = client
    @usage_file = usage_file
  end

  def parse
    case @client.usage_file_format
      when :xml
        parse_xml
      when :csv
        parse_csv
    end

    @client.last_parse = Time.now
    @client.save!
  end

  private

  def parse_xml
    # parse xml
  end

  def parse_csv
    # parse csv
  end
end

class UsageFileParser
  def initialize(client, parser)
    @client = client
    @parser = parser
  end

  def parse(usage_file)
    parser.parse(usage_file)
    @client.last_parse = Time.now
    @client.save!
  end
end

class XmlParser
  def parse(usage_file)
    # parse xml
  end
end

class CsvParser
  def parse(usage_file)
    # parse csv
  end
end

Liskov Substitution

“objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program.” See also design by contract.

una violacion de este principio

class Rectangle
  def set_height(height)
    @height = height
  end

  def set_width(width)
    @width = width
  end
end

class Square < Rectangle
  def set_height(height)
    super(height)
    @width = height
  end

  def set_width(width)
    super(width)
    @height = width
  end
end

Interface Segregation

“many client-specific interfaces are better than one general-purpose interface.”

Dependency Inversion

one should “Depend upon Abstractions. Do not depend upon concretions.” high-level (think business logic) objects not depending on low-level (think database querying and IO) implementation details

class UsageFileParser
  def initialize(client, parser)
    @client = client
    @parser = parser
  end

  def parse(usage_file)
    parser.parse(usage_file)
    @client.last_parse = Time.now
    @client.save!
  end
end

class XmlParser
  def parse(usage_file)
    # parse xml
  end
end

class CsvParser
  def parse(usage_file)
    # parse csv
  end
end

ejemplps extraídos de https://robots.thoughtbot.com/back-to-basics-solid

Lo que siempre debes de hacer

1. Usar un sistema de control de versiones
2. Usar testing
3. Replantear el código que acabas de terminar
4. Refactor
5. No re-inventar la rueda, entender cómo rueda
6. Contribuir al open source <3

Cómo convencer a tu jefe?

No lo hagas!

Agradecemos por las chelas

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