Merge pull request #9 from restoreddev/classes

Updates to classes pages and new strings page

assets/templates/_table_of_contents.phtml

@@ -5,16 +5,18 @@
         <li><a href="<?= page_path('basics') ?>">Basics</a></li>
         <li><a href="<?= page_path('variables') ?>">Variables</a></li>
         <li><a href="<?= page_path('arithmetic') ?>">Arithmetic</a></li>
+        <li><a href="<?= page_path('strings') ?>">Strings</a></li>
         <li><a href="<?= page_path('comparisons') ?>">Comparisons</a></li>
         <li><a href="<?= page_path('boolean-logic') ?>">Boolean Logic</a></li>
         <li><a href="<?= page_path('conditionals') ?>">Conditionals</a></li>
         <li><a href="<?= page_path('loops') ?>">Loops</a></li>
         <li><a href="<?= page_path('arrays') ?>">Arrays</a></li>
         <li><a href="<?= page_path('functions') ?>">Functions</a></li>
-        <li><a href="<?= page_path('classes') ?>">Classes: Introduction</a></li>
+        <li><a href="<?= page_path('classes') ?>">Classes</a></li>
         <li><a href="<?= page_path('classes-inheritance') ?>">Classes: Inheritance</a></li>
         <li><a href="<?= page_path('classes-visibility') ?>">Classes: Visibility</a></li>
         <li><a href="<?= page_path('classes-constructor') ?>">Classes: Constructor</a></li>
+        <li><a href="<?= page_path('static') ?>">Static</a></li>
     </ol>
     <a href="<?= page_path('credits') ?>">Credits</a>
 </div>

code/basics.php

@@ -8,18 +8,16 @@ echo "Hello World!\n";
 // There is a lot going on in this statement so let's work through it.
 
 // First, the echo keyword tells PHP to output some text.
-echo 'I am some text';
+echo "I am some text\n";
 
 // Second, PHP stores text in strings.
 
 // To write a string, you surround letters with single or double quotes.
-// The difference between single quoted strings and double quoted strings
-// is that double quoted strings can hold special characters like \n which tells PHP to start a new line.
-'I am a string';
+// Double quoted strings can hold special characters like \n which tells PHP to start a new line.
 "\nI am a string on a new line";
 
 // Third, all lines of code in PHP must end in a semi-colon.
 echo "No semi-colon is a no-no\n";
 
 // Using semi-colons means we can write multiple statements on one line.
-echo 'Hello'; echo " World\n";
+echo "Hello"; echo " World\n";

code/classes-inheritance.php

@@ -27,7 +27,7 @@ class Tractor extends Vehicle
     }
 }
 
-// Outputs "driving slowly..." instead of "driving...".
+// The drive function now outputs "driving slowly..." instead of "driving...".
 $tractor = new Tractor();
 $tractor->drive();
 

code/classes-visibility.php

@@ -35,7 +35,7 @@ class Phone2
 
 // The "protected" and "private" keywords work a little differently.
 // They both prevent functions and properties from being accessed outside an object.
-// However, a method or property marked "protected" can still be accessed by a child object.
+// However, a method or property marked "protected" can still be accessed by a child class.
 class Phone3
 {
     private $number;
@@ -49,7 +49,7 @@ class Phone3
 }
 
 // In class "Smartphone", the "caller" property is accessible because the parent class
-// has it marked as "protected". However, "Smartphone" cannot access the the "number" property
+// has it marked as "protected". However, "Smartphone" cannot access the "number" property
 // because it is still listed as private.
 class Smartphone extends Phone3
 {

code/classes.php

@@ -43,6 +43,7 @@ class Tricycle
     }
 }
 
+// You can execute a method on an object using the same "->" arrow characters.
 $bike = new Tricycle();
 $bike->color = 'Red';
 $bike->echoColor();

code/static.php

@@ -0,0 +1,70 @@
+<?php
+
+// When writing a class, all of the properties and methods are being defined for the object
+// that will be created from the class.
+
+class House
+{
+    public $color;
+
+    public function __construct($color)
+    {
+        $this->color = $color;
+    }
+}
+
+// Like building a house, a class is a blueprint that
+// defines what the house can do and the object is the house itself that can actually
+// perform the actions defined in the blueprint.
+$house = new House('Green');
+
+// However, what if you want the blueprint to have properties and methods?
+// That is when you use the "static" keyword. In this class, we will define a default color
+// on the class itself and then use it when creating a new object.
+class Skyscraper
+{
+    private static $popularColor;
+    public $color;
+
+    public static function setDefaultColor($color)
+    {
+        self::$popularColor = $color;
+    }
+
+    public function __construct()
+    {
+        $this->color = self::$popularColor;
+    }
+}
+
+// You can access static methods and properties using double colons on "self" inside the object
+// or on the class name outside of the object. Static methods and properties can only access
+// other static methods and properties.
+Skyscraper::setDefaultColor('Grey');
+$skyscraper = new Skyscraper();
+echo $skyscraper->color . "\n";
+
+// Often, you will see static constructors in PHP.
+// A static constructor creates a new instance of an object. Why would do that when you can just use "new Class" to create
+// the object? The most common reason is to make the code more readable.
+class TinyHouse
+{
+    private $color;
+    private $wheels;
+    private $trailer;
+
+    public static function build($color, $wheels, $trailer)
+    {
+        return new self($color, $wheels, $trailer);
+    }
+
+    public function __construct($color, $wheels, $trailer)
+    {
+        $this->color = $color;
+        $this->wheels = $wheels;
+        $this->trailer = $trailer;
+    }
+}
+
+// Using "build" can make more sense than "new", but it is ultimately a personal preference.
+$house = TinyHouse::build('Blue', 4, true);

code/strings.php

@@ -0,0 +1,23 @@
+<?php
+
+// As seen in the first chapter, a string is a group of characters created by
+// surrounding text in single or double quotes.
+$firstname = 'Joey';
+$lastname = "Johnson";
+
+// A double quoted string can interpret special characters starting
+// with a back slash to create formatting. The \n creates a newline
+// between the names and after them.
+echo "Jacob\nJones\n";
+
+// Double quoted strings can also embed variables in the text. This code
+// outputs "Cindy Smith".
+$firstname = 'Cindy';
+echo "$firstname Smith\n";
+
+// Another feature of strings is the ability to combine them together.
+// To combine two strings, use the period character in between them.
+$firstname = 'Jenny';
+$lastname = 'Madison';
+$fullname = $firstname . $lastname;
+echo $fullname;

config.php

@@ -27,12 +27,18 @@ return [
             'title' => 'Arithmetic',
             'subtitle' => 'Doing math like a pro',
             'previous' => 'variables',
+            'next' => 'strings',
+        ]),
+        Page::create('strings', null, 'strings.php', [
+            'title' => 'Strings',
+            'subtitle' => 'Working with text',
+            'previous' => 'arithmetic',
             'next' => 'comparisons',
         ]),
         Page::create('comparisons', null, 'comparisons.php', [
             'title' => 'Comparisons',
             'subtitle' => 'Equality checking',
-            'previous' => 'arithmetic',
+            'previous' => 'strings',
             'next' => 'boolean-logic',
         ]),
         Page::create('boolean-logic', null, 'boolean-logic.php', [
@@ -87,6 +93,12 @@ return [
             'title' => 'Classes: Constructor',
             'subtitle' => 'Construct your objects',
             'previous' => 'classes-visibility',
+            'next' => 'static',
+        ]),
+        Page::create('static', null, 'static.php', [
+            'title' => 'Static',
+            'subtitle' => 'Adding properties and functions to the blueprint',
+            'previous' => 'classes-constructor',
             'next' => '',
         ]),
     ],