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Object Calisthenics Applied to PHP

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Guilherme Blanco

The document presents the concept of Object Calisthenics, a set of programming practices aimed at improving code readability, maintainability, and testability in object-oriented programming. It outlines nine rules to follow, such as limiting indentation levels per method and avoiding the use of the 'else' keyword, as well as emphasizing the importance of small entities and collections. These practices are derived from a need for better code structure and encapsulation in PHP programming.

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Object Calisthenics Applied to PHP
Object Calisthenics The speaker @guilhermeblanco http://github.com/guilhermeblanco
Object Calisthenics Agenda ‣ Motivation ‣ Rules ‣ Application
Object Calisthenics Erm... WTH is Object Calisthenics? ‣ Object Calisthenics
Object Calisthenics Erm... WTH is Object Calisthenics? ‣ Object Calisthenics Term derived from greek, “exercise”, under the context of gymnastics.
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
Object Calisthenics Motivation ‣ Readable Code ‣ Comprehensible ‣ Testable ‣ Maintainable Learning about good code practices at Object CaIisthenics talk of @guilhermeblanco on @gtaphp
Object Calisthenics Rules ‣ Nine (9) rules “very” simple...
Object Calisthenics Rule 1: Only one indentation level per method ‣ Only one indentation level per method
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 $input; }
Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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 $input; }
Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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 $input; }
Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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();' ); } } } }
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( "{$message}", 3, 'javascript:history.back();' ); } } } }
Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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( $errorMessage, 3, 'javascript:history.back();' ); } } }
Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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( $errorMessage, 3, 'javascript:history.back();' ); } } }
Object Calisthenics Rule 1: Only one indentation level per method public function validatePost($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( $errorMessage, 3, 'javascript:history.back();' ); } }
Object Calisthenics Rule 1: Only one indentation level per method public function validatePost($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();' ); } }
Object Calisthenics Rule 2: Do not use the “else” keyword ‣ Never use the “else” keyword
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'); } }
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'); } }
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'); } }
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); }
Object Calisthenics Rule 3: Wrap primitive types and strings ‣ Wrap all primitive types and strings
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
Object Calisthenics Rule 3: Wrap primitive types and strings ‣ But... if the variable of primitive type has a behavior, it must be encapsulated
Object Calisthenics Rule 3: Wrap primitive types and strings class UIComponent { ! // ... ! public function repaint($animate = true) { // ... } } // ... $component->repaint(false);
Object Calisthenics Rule 3: Wrap primitive types and strings class UIComponent { ! // ... ! public function repaint($animate = true) { // ... } } // ... $component->repaint(false);
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));
Object Calisthenics Rule 4: Only one dot per line ‣ Only one dot (arrow for PHP) per line
Object Calisthenics Rule 4: Only one dot per line ‣ Not applicable to PHP...
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
Object Calisthenics Rule 4: Only one dot per line ‣ We could adapt to the language, contemplating...
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();
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());
Object Calisthenics Rule 5: Do not abbreviate ‣ Do not abbreviate
Object Calisthenics Rule 5: Do not abbreviate
Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate?
Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate? ‣ Write the same name repeatedly?
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.
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?
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).
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).
Object Calisthenics Rule 6: Keep your entities small ‣ Keep your entities small
Object Calisthenics Rule 6: Keep your entities small ‣ Original rule: 50 lines per class
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.
Object Calisthenics Rule 7: Do not create classes with more than 2 instance variables ‣ Do not create classes with more than 2 instance variables
Object Calisthenics Rule 7: Do not create classes with more than 2 instance variables ‣ Objective: ‣ Low cohesion ‣ Better encapsulation
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
Object Calisthenics Rule 8: Use first class collections ‣ Use first class collections
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
Object Calisthenics Rule 8: Use first class collections ‣ Objectives: ‣ Specific behaviors have a good place to stay ‣ Filtering, combining, mapping, ...
Object Calisthenics Rule 8: Use first class collections ‣ DoctrineCommonCollectionsArrayCollection ‣ Countable ‣ IteratorAggregate (inherits Traversable) ‣ ArrayAccess
Object Calisthenics Rule 9: Do not create getter/setter methods to properties ‣ Do not create getter/setter methods to properties
Object Calisthenics Rule 9: Do not create getter/setter methods to properties ‣ Non-applicable to PHP due to language’s nature
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); } // ... }
Object Calisthenics “Rule 10”: Document your code! ‣ Document your code!!!!!!!!!!!!!!!!!
Object Calisthenics That’s all folks! ‣ Questions? @guilhermeblanco http://github.com/guilhermeblanco

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Object Calisthenics Applied to PHP

  • 1. Object Calisthenics Applied to PHP
  • 2. Object Calisthenics The speaker @guilhermeblanco http://github.com/guilhermeblanco
  • 4. Object Calisthenics Erm... WTH is Object Calisthenics? ‣ Object Calisthenics
  • 5. Object Calisthenics Erm... WTH is Object Calisthenics? ‣ Object Calisthenics Term derived from greek, “exercise”, under the context of gymnastics.
  • 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. Object Calisthenics Motivation ‣ Readable Code ‣ Comprehensible ‣ Testable ‣ Maintainable Learning about good code practices at Object CaIisthenics talk of @guilhermeblanco on @gtaphp
  • 8. Object Calisthenics Rules ‣ Nine (9) rules “very” simple...
  • 9. Object Calisthenics Rule 1: Only one indentation level per method ‣ Only one indentation level per method
  • 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 $input; }
  • 11. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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 $input; }
  • 12. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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 $input; }
  • 13. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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. 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( "{$message}", 3, 'javascript:history.back();' ); } } } }
  • 15. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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( $errorMessage, 3, 'javascript:history.back();' ); } } }
  • 16. Object Calisthenics Rule 1: Only one indentation level per method public function validateForm($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( $errorMessage, 3, 'javascript:history.back();' ); } } }
  • 17. Object Calisthenics Rule 1: Only one indentation level per method public function validatePost($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( $errorMessage, 3, 'javascript:history.back();' ); } }
  • 18. Object Calisthenics Rule 1: Only one indentation level per method public function validatePost($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. Object Calisthenics Rule 2: Do not use the “else” keyword ‣ Never use the “else” keyword
  • 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. 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. 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. 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. Object Calisthenics Rule 3: Wrap primitive types and strings ‣ Wrap all primitive types and strings
  • 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. Object Calisthenics Rule 3: Wrap primitive types and strings ‣ But... if the variable of primitive type has a behavior, it must be encapsulated
  • 27. Object Calisthenics Rule 3: Wrap primitive types and strings class UIComponent { ! // ... ! public function repaint($animate = true) { // ... } } // ... $component->repaint(false);
  • 28. Object Calisthenics Rule 3: Wrap primitive types and strings class UIComponent { ! // ... ! public function repaint($animate = true) { // ... } } // ... $component->repaint(false);
  • 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. Object Calisthenics Rule 4: Only one dot per line ‣ Only one dot (arrow for PHP) per line
  • 31. Object Calisthenics Rule 4: Only one dot per line ‣ Not applicable to PHP...
  • 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. Object Calisthenics Rule 4: Only one dot per line ‣ We could adapt to the language, contemplating...
  • 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. 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. Object Calisthenics Rule 5: Do not abbreviate ‣ Do not abbreviate
  • 37. Object Calisthenics Rule 5: Do not abbreviate
  • 38. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate?
  • 39. Object Calisthenics Rule 5: Do not abbreviate ‣ Think about it... why do you want to abbreviate? ‣ Write the same name repeatedly?
  • 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. 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. 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. 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. Object Calisthenics Rule 6: Keep your entities small ‣ Keep your entities small
  • 45. Object Calisthenics Rule 6: Keep your entities small ‣ Original rule: 50 lines per class
  • 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. 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. Object Calisthenics Rule 7: Do not create classes with more than 2 instance variables ‣ Objective: ‣ Low cohesion ‣ Better encapsulation
  • 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. Object Calisthenics Rule 8: Use first class collections ‣ Use first class collections
  • 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. Object Calisthenics Rule 8: Use first class collections ‣ Objectives: ‣ Specific behaviors have a good place to stay ‣ Filtering, combining, mapping, ...
  • 53. Object Calisthenics Rule 8: Use first class collections ‣ DoctrineCommonCollectionsArrayCollection ‣ Countable ‣ IteratorAggregate (inherits Traversable) ‣ ArrayAccess
  • 54. Object Calisthenics Rule 9: Do not create getter/setter methods to properties ‣ Do not create getter/setter methods to properties
  • 55. Object Calisthenics Rule 9: Do not create getter/setter methods to properties ‣ Non-applicable to PHP due to language’s nature
  • 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. Object Calisthenics “Rule 10”: Document your code! ‣ Document your code!!!!!!!!!!!!!!!!!
  • 58. Object Calisthenics That’s all folks! ‣ Questions? @guilhermeblanco http://github.com/guilhermeblanco

Editor's Notes