String containing function-line. How to echo in other file? - php

Question

$str = "$obj = new class(); $obj->getSomeFunction();"
Is this possible? I am trying to develop a very dynamic platform to base my website off of.
Anyway to get this working? From a string by "echo $str;" it will make the object and run the function?

Answer 1

Instead of passing an object as a string, just create a new instance of your object. And once you've included a file.. All variables, objects, etc. exist in the file that includes that file.
Edit:
Instead of passing a class as a string, you can create classes dynamically:
<?php
class cc {
function __construct() {
echo 'hi!';
}
}
$type = 'cc';
$obj = new $type; // outputs "hi!"
?>
Alternatively you can use static classes:
<?php
class Foo {
public static function aStaticMethod() {
echo 'hi!';
}
}
Foo::aStaticMethod(); // outputs "hi!"
// or:
$classname = 'Foo';
$classname::aStaticMethod(); // outputs "hi!"
?>

Answer 2

I am in the process of writing my own mvc framework(as an learning project), and needed to dynamically create objects and call a method. I ended up using the reflection api in order to create a new instance of the object and then call the method. in this case i ended up passing an associative array that had two key/value pairs, the class name, and the method I wanted to call. I hope this helps.
$class = $command['class'];
$method = $command['method'];
try{
$reflectorClass = new ReflectionClass($class);
$reflectedInstance = $reflectorClass->newInstance($matches);
} catch (Exception $e) {
exceptionHandler::catchException($e);
}
try {
$reflectorMethod = new ReflectionMethod($reflectedInstance, $method);
$reflectorMethod->invoke($reflectedInstance);
} catch (Exception $e) {
exceptionHandler::catchException($e);
}

Answer 3

In PHP included files are executed when you call include() or require(). They follow variable scope rules and even allow you to return results as if the include was a function like so:
dynamicPlatform.php
<?php
$object = include('createObjAndDoStuff.php');
?>
createObjAndDoStuff.php
<?php
$obj = new class();
$obj->getSomeFunction();
return $obj;
?>
As #zerkms has pointed out, you probably should be using factories.
class Factory {
public static function someclass() {
include_once('./classes/someclass.php'); //Although some discourage the use of *_once() functions
$obj = new someclass();
$obj->getSomeFunction();
return $obj;
}
}
//And to get a new class instance
$object = Singleton::someclass();
Or pseudo-singletons with factories:
class SingletonFactory {
private static $someclass;
public static function someclass() {
if(!self::$someclass) {
include('./classes/someclass.php');
self::$someclass = new someclass();
self::$someclass->getSomeFunction();
}
return self::$someclass;
}
}

Answer 4

What you are searching for is eval but while it will do exactly what you are asking for, it's considered bad solution and can lead to messy code.
You can just include file that contains PHP code, or you can serialize meta data about the actions to be performed and then parse that data.
Depending on what you are trying to achieve, you may be interested in serializing objects in session as well as in Command Pattern (a way to encapsulate set of operations in object(s))