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Object Calisthenics Applied to PHP

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Object Calisthenics Applied to PHP

  1. 1. Object Calisthenics Applied to PHP
  2. 2. Object Calisthenics The speaker @guilhermeblanco http://github.com/guilhermeblanco
  3. 3. Object Calisthenics Agenda ‣ Motivation ‣ Rules ‣ Application
  4. 4. Object Calisthenics Erm... WTH is Object Calisthenics? ‣ Object Calisthenics
  5. 5. Object Calisthenics Erm... WTH is Object Calisthenics? ‣ Object Calisthenics Term derived from greek, “exercise”, under the context of gymnastics.
  6. 6. Object Calisthenics Erm... WTH is Object Calisthenics? ‣ Jeff Bay in The ThoughtWorks Anthology [1] coined the term Object Calisthenics in computers, as a group of exercises to Object Oriented programming. [1] The ThoughtWorks Anthology: Essays on Software Technology and Innovation
  7. 7. Object Calisthenics Motivation ‣ Readable Code ‣ Comprehensible ‣ Testable ‣ Maintainable Learning about good code practices at Object CaIisthenics talk of @guilhermeblanco on @gtaphp
  8. 8. Object Calisthenics Rules ‣ Nine (9) rules “very” simple...
  9. 9. Object Calisthenics Rule 1: Only one indentation level per method ‣ Only one indentation level per method
  10. 10. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($filters='', $validators='', $options='') { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); if ($input->hasInvalid() || $input->hasMissing()) { foreach ($input->getMessages() as $field => $messageList) { foreach ($messageList as $message) { if (strpos($message, "empty")) { throw new Tss_FormException( "The field {$field} cannot be empty!", 3, 'javascript:history.back();' ); } else { throw new Tss_FormException( "{$message}", 3, 'javascript:history.back();' ); } } } } return $input; }
  11. 11. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($filters='', $validators='', $options='') { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); 0 if ($input->hasInvalid() || $input->hasMissing()) { 1 foreach ($input->getMessages() as $field => $messageList) { 2 foreach(strpos($message, "empty")) { ($messageList as $message) { 3 if throw new Tss_FormException( 4 "The field {$field} cannot be empty!", 3, 'javascript:history.back();' ); } else { throw new Tss_FormException( "{$message}", 3, 'javascript:history.back();' ); } } } } return $input; }
  12. 12. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($filters='', $validators='', $options='') { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); 0 if ($input->hasInvalid() || $input->hasMissing()) { 1 foreach ($input->getMessages() as $field => $messageList) { 2 foreach(strpos($message, "empty")) { ($messageList as $message) { 3 if throw new Tss_FormException( 4 "The field {$field} cannot be empty!", 3, 'javascript:history.back();' ); } else { throw new Tss_FormException( "{$message}", 3, 'javascript:history.back();' ); } } } } return $input; }
  13. 13. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($filters = array(), $validators = array(), $options = null) { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); if ( ! ($input->hasInvalid() || $input->hasMissing())) { return $input; } foreach ($input->getMessages() as $field => $messageList) { foreach ($messageList as $message) { if (strpos($message, "empty")) { throw new Tss_FormException( "The field {$field} cannot be empty!", 3, 'javascript:history.back();' ); } else { throw new Tss_FormException( "{$message}", 3, 'javascript:history.back();' ); } } } }
  14. 14. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($filters = array(), $validators = array(), $options = null) { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); if ( ! ($input->hasInvalid() || $input->hasMissing())) { return $input; } 0 foreach ($input->getMessages() as $field => $messageList) { 1 foreach(strpos($message, "empty")) { ($messageList as $message) { 2 if throw new Tss_FormException( 3 "The field {$field} cannot be empty!", 3, 'javascript:history.back();' ); } else { throw new Tss_FormException( "{$message}", 3, 'javascript:history.back();' ); } } } }
  15. 15. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($filters = array(), $validators = array(), $options = null) { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); if ( ! ($input->hasInvalid() || $input->hasMissing())) { return $input; } foreach ($input->getMessages() as $field => $messageList) { foreach ($messageList as $message) { $errorMessage = (strpos($message, "empty") === false) ? "The field {$field} cannot be empty!" : "{$message}"; throw new Tss_FormException( $errorMessage, 3, 'javascript:history.back();' ); } } }
  16. 16. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($filters = array(), $validators = array(), $options = null) { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); if ( ! ($input->hasInvalid() || $input->hasMissing())) { return $input; } 0 foreach ($input->getMessages() as $field => $messageList) { 1 foreach ($messageList as $message) { "empty") === false) 2 $errorMessage = (strpos($message,be empty!" ? "The field {$field} cannot : "{$message}"; throw new Tss_FormException( $errorMessage, 3, 'javascript:history.back();' ); } } }
  17. 17. Object Calisthenics Rule 1: Only one indentation level per method public function validatePost($filters = array(), $validators = array(), $options = null) { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); if ( ! ($input->hasInvalid() || $input->hasMissing())) { return $input; } foreach ($input->getMessages() as $field => $message) { $messageKey = key($message); $message = $message[$messageKey]; $errorMessage = (strpos($message, "empty") === false) ? "The field {$field} cannot be empty!" : "{$message}"; throw new Tss_FormException( $errorMessage, 3, 'javascript:history.back();' ); } }
  18. 18. Object Calisthenics Rule 1: Only one indentation level per method public function validatePost($filters = array(), $validators = array(), $options = null) { $data = $_POST; $input = new Zend_Filter_Input($filters, $validators, $data, $options); $input->setDefaultEscapeFilter(new Zend_Filter_StringTrim()); if ( ! ($input->hasInvalid() || $input->hasMissing())) { return $input; } foreach ($input->getMessages() as $field => $message) { $messageKey = key($message); $message = $message[$messageKey]; $errorMessage = (strpos($message, "empty") === false) ? "The field {$field} cannot be empty!" : "{$message}"; throw new Tss_FormException( $errorMessage, 3, 'javascript:history.back();' ); } }
  19. 19. Object Calisthenics Rule 2: Do not use the “else” keyword ‣ Never use the “else” keyword
  20. 20. Object Calisthenics Rule 2: Do not use the “else” keyword function login() { $login = $this->input->post('email', true); $password = $this->input->post('password', true); $reference = $this->input->post('reference', true); if ($this->clients_model->login($login, $password)) { redirect($reference); } else { $this->session->set_flashdata('error', 'User or password invalid.'); $this->session->set_flashdata('reference', $reference); redirect('clients'); } }
  21. 21. Object Calisthenics Rule 2: Do not use the “else” keyword function login() { $login = $this->input->post('email', true); $password = $this->input->post('password', true); $reference = $this->input->post('reference', true); if ($this->clients_model->login($login, $password)) { redirect($reference); } else { $this->session->set_flashdata('error', 'User or password invalid.'); $this->session->set_flashdata('reference', $reference); redirect('clients'); } }
  22. 22. Object Calisthenics Rule 2: Do not use the “else” keyword function login() { $login = $this->input->post('email', true); $password = $this->input->post('password', true); $reference = $this->input->post('reference', true); if ($this->clients_model->login($login, $password)) { redirect($reference); } else { $this->session->set_flashdata('error', 'User or password invalid.'); $this->session->set_flashdata('reference', $reference); redirect('clients'); } }
  23. 23. Object Calisthenics Rule 2: Do not use the “else” keyword function login() { $login = $this->input->post('email', true); $password = $this->input->post('password', true); $reference = $this->input->post('reference', true); if ( ! ($this->clients_model->login($login, $password))) { $this->session->set_flashdata('error', 'User or password invalid.'); $this->session->set_flashdata('reference', $reference); $reference = 'clients'; } redirect($reference); }
  24. 24. Object Calisthenics Rule 3: Wrap primitive types and strings ‣ Wrap all primitive types and strings
  25. 25. Object Calisthenics Rule 3: Wrap primitive types and strings ‣ This rule cannot be completely ported to PHP, because the language does not perform well with an entirely Object Oriented code with a huge amount of instances
  26. 26. Object Calisthenics Rule 3: Wrap primitive types and strings ‣ But... if the variable of primitive type has a behavior, it must be encapsulated
  27. 27. Object Calisthenics Rule 3: Wrap primitive types and strings class UIComponent { ! // ... ! public function repaint($animate = true) { // ... } } // ... $component->repaint(false);
  28. 28. Object Calisthenics Rule 3: Wrap primitive types and strings class UIComponent { ! // ... ! public function repaint($animate = true) { // ... } } // ... $component->repaint(false);
  29. 29. Object Calisthenics Rule 3: Wrap primitive types and strings class UIComponent { ! // ... ! public function repaint(Animate $animate) { // ... } } class Animate { public $animate; public function __construct($animate = true) { $this->animate = $animate; } } // ... $component->repaint(new Animate(false));
  30. 30. Object Calisthenics Rule 4: Only one dot per line ‣ Only one dot (arrow for PHP) per line
  31. 31. Object Calisthenics Rule 4: Only one dot per line ‣ Not applicable to PHP...
  32. 32. Object Calisthenics Rule 4: Only one dot per line ‣ ...but multiple nested calls... ‣ tend to expose an encapsulation problem ‣ increase difficulty to debug and exception handling ‣ do not represent an atomic action
  33. 33. Object Calisthenics Rule 4: Only one dot per line ‣ We could adapt to the language, contemplating...
  34. 34. Object Calisthenics Rule 4: Only one dot per line ‣ A chain of different objects, but only if the execution only includes getters and setters $user->getLocationPoint()->getCountry()->getName();
  35. 35. Object Calisthenics Rule 4: Only one dot per line ‣ A chain of a unique object, through the usage of a fluent interface $filterChain->addFilter(new Zend_Filter_Alpha()) ->addFilter(new Zend_Filter_StringToLower());
  36. 36. Object Calisthenics Rule 5: Do not abbreviate ‣ Do not abbreviate
  37. 37. Object Calisthenics Rule 5: Do not abbreviate
  38. 38. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate?
  39. 39. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate? ‣ Write the same name repeatedly?
  40. 40. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate? ‣ Write the same name repeatedly? ‣ Then your method is reused multiple times, signalling a code duplication.
  41. 41. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate? ‣ Write the same name repeatedly? ‣ Then your method is reused multiple times, signalling a code duplication. ‣ Method name too long?
  42. 42. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate? ‣ Write the same name repeatedly? ‣ Then your method is reused multiple times, signalling a code duplication. ‣ Method name too long? ‣ Maybe your class has multiple responsibilities or it is missing a helper class (bad architecture).
  43. 43. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate? ‣ Write the same name repeatedly? ‣ Then your method is reused multiple times, signalling a code duplication. ‣ Method name too long? ‣ Maybe your class has multiple responsibilities or it is missing a helper class (bad architecture).
  44. 44. Object Calisthenics Rule 6: Keep your entities small ‣ Keep your entities small
  45. 45. Object Calisthenics Rule 6: Keep your entities small ‣ Original rule: 50 lines per class
  46. 46. Object Calisthenics Rule 6: Keep your entities small ‣ Adapted to PHP: 100 lines per class and no more than 15 classes per package. ‣ The change is necessary because of the lack of rule for documentation, which can easily occupy up to 50% of the lines of a class.
  47. 47. Object Calisthenics Rule 7: Do not create classes with more than 2 instance variables ‣ Do not create classes with more than 2 instance variables
  48. 48. Object Calisthenics Rule 7: Do not create classes with more than 2 instance variables ‣ Objective: ‣ Low cohesion ‣ Better encapsulation
  49. 49. Object Calisthenics Rule 7: Do not create classes with more than 2 instance variables ‣ The original rule points to 2 instance variables ‣ To PHP, the suggestion is no more than 5 variables
  50. 50. Object Calisthenics Rule 8: Use first class collections ‣ Use first class collections
  51. 51. Object Calisthenics Rule 8: Use first class collections ‣ The rule is simple: Any class that contains a collection (array to PHP), cannot contain any other properties
  52. 52. Object Calisthenics Rule 8: Use first class collections ‣ Objectives: ‣ Specific behaviors have a good place to stay ‣ Filtering, combining, mapping, ...
  53. 53. Object Calisthenics Rule 8: Use first class collections ‣ DoctrineCommonCollectionsArrayCollection ‣ Countable ‣ IteratorAggregate (inherits Traversable) ‣ ArrayAccess
  54. 54. Object Calisthenics Rule 9: Do not create getter/setter methods to properties ‣ Do not create getter/setter methods to properties
  55. 55. Object Calisthenics Rule 9: Do not create getter/setter methods to properties ‣ Non-applicable to PHP due to language’s nature
  56. 56. Object Calisthenics Rule 9: Do not create getter/setter methods to properties /** * THIS CLASS WAS GENERATED BY THE DOCTRINE ORM. DO NOT EDIT THIS FILE. */ class ApplicationCoreDomainUserModelUserProxy ! extends ApplicationCoreDomainUserModelUser ! implements DoctrineORMProxyProxy { // ... public function getId() { $this->__load(); return parent::getId(); } public function setId($id) { $this->__load(); return parent::setId($id); } // ... }
  57. 57. Object Calisthenics “Rule 10”: Document your code! ‣ Document your code!!!!!!!!!!!!!!!!!
  58. 58. Object Calisthenics That’s all folks! ‣ Questions? @guilhermeblanco http://github.com/guilhermeblanco

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