prevent double constructor call

Author: mle86

CHANGELOG.md

@@ -1,3 +1,6 @@
+v1.0.2 (2017-04)
+* prevent double constructor call
+
 v1.0.1 (2017-01-12)
 * renamed "aux" directory
 * more examples

src/Value/AbstractValue.php

@@ -50,6 +50,15 @@ final public function value () {
 	}
 
 
+	/**
+	 * This variable is used to prevent double constructor calls,
+	 * which could otherwise be used to change the wrapped value.
+	 *
+	 * @var bool
+	 */
+	private $is_set = false;
+
+
 	/**
 	 * The constructor uses the subclass' IsValid method to test its input
 	 * argument.  Valid values are stored in the new instance,  invalid values
@@ -66,6 +75,11 @@ final public function value () {
 	 */
 	public function __construct ($raw_value) {
 
+		if ($this->is_set) {
+			throw new DoubleConstructorCallException ("double constructor call is not allowed");
+		}
+		$this->is_set = true;
+
 		if ($raw_value instanceof static) {
 			/* Re-wrapping an existing instance works,
 			 * the contained value has already passed the IsValid check once.  */

src/Value/DoubleConstructorCallException.php

@@ -0,0 +1,8 @@
+<?php
+namespace mle86\Value;
+
+class DoubleConstructorCallException
+	extends \BadMethodCallException
+{
+}
+

test/90-DoubleConstructorCallTest.php

@@ -0,0 +1,54 @@
+<?php
+namespace mle86\Value\Tests;
+
+use mle86\Value\AbstractValue;
+use mle86\Value\Value;
+require_once 'helpers/TestWrapper4.php';
+
+
+/**
+ * Ensures that the class constructor
+ * cannot be used to change the stored value.
+ */
+class DoubleConstructorCallTest
+	extends \PHPUnit_Framework_TestCase
+{
+
+	const VALID_VALUE1 = "41111";
+	const VALID_VALUE2 = "42222";
+
+	/**
+	 * @return Value
+	 */
+	public function testInstance () {
+		$tw = new TestWrapper4 (self::VALID_VALUE1);
+
+		$this->assertTrue(($tw && $tw instanceof TestWrapper4 && $tw instanceof AbstractValue && $tw instanceof Value),
+			"new TestWrapper4() did not result in a valid object");
+
+		$this->assertSame(self::VALID_VALUE1, $tw->value());
+
+		return $tw;
+	}
+
+	/**
+	 * @depends testInstance
+	 */
+	public function testDoubleConstructorCall (Value $o) {
+		try {
+			$o->__construct(self::VALID_VALUE2);
+		} catch (\Throwable $e) {
+			// Okay, this produced an exception.
+			// But we still need to check the value...
+		}
+
+		$this->assertNotEquals(self::VALID_VALUE2, $o->value(),
+			"Stored value can be CHANGED with a double constructor call!");
+		$this->assertNotNull($o->value(),
+			"Stored value was RESET by a double constructor call!");
+		$this->assertEquals(self::VALID_VALUE1, $o->value(),
+			"Stored value was UNEXPECTEDLY ALTERED by a double constructor call!");
+	}
+
+}
+