Dynamic class usage in PHP - php

Question

I am writing a program which processes geographical coordinates of a city and I want to randomly select my city in each run; the process for all cities are the same.
I have a PHP class for each city which contains geographical coordinates of it; for example:
<?php
namespace Utility\Locations;
class Tehran
{
const MIN_LAT = 35.325;
const MAX_LAT = 35.390;
const MIN_LNG = 51.165;
const MAX_LNG = 51.230;
}
In another PHP file I make use of the class as:
use Utility\Locations\Tehran;
use Utility\Locations\Karaj;
...
protected function MyProcessingMethod () {
...
$city = Faker::create()->randomElement(array("Tehran", "Karaj"));
echo $city::MIN_LAT;
...
}
...
If it helps, the above mentioned file is a CodeCeption Cest and MyProcessingMethod is used as a DataProvider. When I run my tests using codecept run scenarios/MyCest.php, I get this error:
PHP Fatal error: Uncaught Error: Class 'Tehran' not found in /home/zeinab/PhpstormProjects/test/scenarios/MyCest.php:190
Stack trace:
#0 [internal function]: MyCest->MyProcessingMethod()
#1 /home/zeinab/PhpstormProjects/test/vendor/codeception/codeception/src/Codeception/Util/ReflectionHelper.php(47): ReflectionMethod->invokeArgs(Object(MyCest), Array)
#2 /home/zeinab/PhpstormProjects/test/vendor/codeception/codeception/src/Codeception/Test/Loader/Cest.php(65): Codeception\Util\ReflectionHelper::invokePrivateMethod(Object(MyCest), Object(ReflectionMethod))
#3 /home/zeinab/PhpstormProjects/test/vendor/codeception/codeception/src/Codeception/Test/Loader.php(109): Codeception\Test\Loader\Cest->loadTests('/home/zeinab/Ph...')
#4 /home/zeinab/PhpstormPro in /home/zeinab/PhpstormProjects/test/scenarios/MyCest.php on line 190
I've read PHP official documentations on this type of usage, but all examples there were using the classes that are defined inside destination file.
I also tried this:
$city = Faker::create()->randomElement(array(Tehran::class, Karaj::class));
echo $city::MIN_LAT;
But I got the same error.
Is there anyway to do what I want to?
EDIT 1:
I have put the path to the classes in psr-4 tag of my composer.json:
"autoload": {
"psr-4": {
"Utility\\": "Utility/"
}
}
It seems there is no problem in loading the classes, since using them directly works fine. For example the following code is doing great:
echo Tehran::MIN_LAT;

Answer 1

I created this code snippet for example purposes - so it may not fully reflect your methods but the answer is the principle :)
<?php
# create our city classes
class Brighton
{
const X = 1;
const Y = 2;
}
class London
{
const X = 3;
const Y = 4;
}
# create our get city class
class Foo
{
public function getCity()
{
$possibleCities = ['Brighton', 'London', 'Birmingham']; # add a city that's not a class for testing
$city = rand(0, count($possibleCities) -1);
return $possibleCities[$city];
}
}
# init foo
$foo = new Foo();
$city = $foo->getCity(); # get city
# check if class exists, if it does, init it
$cityClass = (class_exists($city) ? new $city() : null);
# check if class is empty - if it isn't echo CONST X
echo (!empty($cityClass) ? $cityClass::X : $city. ' class not found');
How to include the classes (if they're in separate files):
Imagine the tree is:
|-app
|-----core
|---------city
|-------------Brighton.php
|-------------London.php
|-----Foo.php
In Foo.php
<?php
require_once 'city/Brighton.php';
require_once 'city/London.php';
use City\Brighton;
use City\London;
# etc. etc
And then Brighton.php and London.php have the namespace of City:
<?php
namespace City;
class Brighton
{} # etc

Answer 2

add loader to first line of your code :
function loader($className)
{
$fileName = str_replace('\\', '/', $className) . '.php';
require_once $fileName;
}
spl_autoload_register('loader');
then use namespaces like directory structures :
Ahvaz.php in app/core/city directory
namespace app\core\city;
class Ahvaz
{
//...
}
when you load a class Ahvaz.php like this
$var = new Ahvaz();
you need to add use app\core\city;
then you have :
use app\core\city;
$var = new Ahvaz();
it will include Ahvaz.php from app/core/city directory