Added exceptions to gpio class

composer.lock

@@ -1,7 +1,8 @@
 {
     "_readme": [
         "This file locks the dependencies of your project to a known state",
-        "Read more about it at http://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file"
+        "Read more about it at http://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
+        "This file is @generated automatically"
     ],
     "hash": "6ede4cbc5ab4ef05b58811c306b5376f",
     "packages": [

examples/basic.php

@@ -23,7 +23,7 @@ $led = $gpio[0]
     ->setLabel("red led")
     ->dumpStatus(true);
 
-$btn = $gpio[1]
+$btn1 = $gpio[1]
     ->setDirection("input")
     ->setValue(0)
     ->setEdge("rising")
@@ -31,7 +31,7 @@ $btn = $gpio[1]
     ->setLabel("button 1")
     ->dumpStatus(true);
 
-$gpio[2]
+$btn2 = $gpio[2]
     ->setDirection("input")
     ->setValue(0)
     ->setEdge("rising")

lib/Exception/HardwareException.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace NoccyLabs\Gpio\Exception;
+
+use NoccyLabs\Gpio\GpioPin;
+
+class HardwareException extends \Exception
+{
+}

lib/Gpio.php

@@ -19,12 +19,24 @@
 
 namespace NoccyLabs\Gpio;
 
+use NoccyLabs\Gpio\Exception\HardwareException;
+
 class Gpio implements \ArrayAccess
 {
     protected $gpio = array();
     
     /** @var NoccyLabs\Gpio\GpioMapperInterface */
     protected $mapper;
+    
+    public function __construct()
+    {
+        if (!file_exists("/sys/gpio")) {
+            throw new HardwareException("gpio sysfs is not available");
+        }
+        if (!is_writable("/sys/gpio/export")) {
+            throw new HardwareException("gpio sysfs is not writable");
+        }
+    }
 
     public function refresh()
     {

lib/GpioPin.php

@@ -137,7 +137,7 @@ class GpioPin
     public function dumpStatus($ansi=false)
     {
         if ($ansi) {
-            $status = "\e[43;37;1m          GPIO{$this->pin}          \e[0m\n";
+            $status = "\e[44;37;1m          GPIO{$this->pin}          \e[0m\n";
             $direction = "\e[36;1m".
                 ($this->direction=="input"?(CS::chr(0x2190)):(CS::chr(0x2192))).
                 "\e[0m ".$this->direction;