I want to create objects dynamically. Right now I'm creating them manually like this
$obj1 = new Prefix_Myobj();
$obj2 = new Prefix_Other();
$obj3 = new Prefix_Another();
How can I set the part after Prefix_ dynamically? I tried this but it didn't work
$name = 'Myobj';
$obj1 = new Prefix_{$name}();
You need to create a string that specifies the entire class name.
$name = 'Myobj';
$classname = 'Prefix_'.$name;
$obj1 = new $classname();
However, it might be better design to build a class registry of sorts rather than generating class names on the fly like this.
Why do you need this? Maybe there is a better solution for your problem; multiton or dependency injection etc...
It is important to say that if your class is in a specific namespace, you need to inform the full path. Example:
namespace my\path\app;
class MyClass {
$name = 'Myobj';
$classname = 'my\path\app\Prefix_' . $name;
$obj1 = new $classname();
}
Related
Before I could create an object in this way in PHP:
use myFolder\models\Document;
$nameClass = 'Document';
$model = new $nameClass;
This used to work without problems.
But now it gives me a error
Is it for the PHP version or configuration?
What is the problem?
Why it sentence works fine?
$model = new Document;
and the previous one fails?
Thanks
The problem was the namespace; it should have been
use myFolder\models\Document;
$nameClass = 'myFolder\models\Document';
$model = new $nameClass;
<?php
namespace Vendor\Package;
$test1 = new Foo\Bar(); // works as usual
$test2 = 'Foo\Bar';
$test2 = new $test2(); // does not work
$test3 = 'Vendor\Package\Foo\Bar';
$test3 = new $test3(); // but this works
I was looking to use $test2 but it doesn't work even though it looks like it should as it's pretty much the same as $test3 which worked.
Is this expected or is there some syntax I need to use for test2 to work?
When you use a dynamic class name, it has to be fully qualified. The documentation says:
One must use the fully qualified name (class name with namespace prefix). Note that because there is no difference between a qualified and a fully qualified Name inside a dynamic class name, function name, or constant name, the leading backslash is not necessary.
Foo\Bar is not fully qualified, it's relative to Vendor\Package that you selected with the earlier namespace statement.
You can prefix your strign with __NAMESPACE__
Vendor\Package\Foo\Bar::__construct
Vendor\Package\Foo\Bar::__construct
Vendor\Package\Foo\Bar::__construct
Repl.it : https://repl.it/repls/BuzzingFairSuperuser
namespace Vendor\Package\Foo;
class Bar
{
function __construct()
{
echo __METHOD__,"\n";
}
}
namespace Vendor\Package;
$test1 = new Foo\Bar(); // works
$test2 = __NAMESPACE__.'\Foo\Bar';
$test2 = new $test2(); // works
$test3 = 'Vendor\Package\Foo\Bar';
$test3 = new $test3(); // works
So I'll see if I can explain this simply. In your first instance "$test1 = new Foo\Bar();", the path to the model is mapped during compile/load time. In the case where "$test2 = 'Foo\Bar'; $test2 = new $test2();", you're trying to call this model during runtime... Unfortunately, at runtime, the linking has already been done, and is not revisited. What this means it that "$test2 = '\Vendor\Package\Foo\Bar'" should work, but a shortened version of the name can't work, as the linking step is not revisited during runtime.
$map_class_name = __NAMESPACE__.'\\'.$map_class_name;
$map = new $map_class_name;
Is it possible to do this in one line like this?
$map = new (__NAMESPACE__.'\\'.$map_class_name);
The above gives
syntax error, unexpected '('
The answer is no, you can't use new with string or expression.
But you can use
$map = new $map_class_name;
Since you use class from current namespace(__NAMESPACE__) you don't have to prefix classname, namespace will be implied.
Alternative solutions
You might use Reflection
$map = (new \ReflectionClass(__NAMESPACE__."\\$map_class_name"))->newInstance();
Another way is to not break line, but I guess this misses the point.
$map_class_name = __NAMESPACE__.'\\'.$map_class_name; $map = new $map_class_name;
IIFE is also possible
$map = (function($n){return new $n;})(__NAMESPACE__."\\$map_class_name");
I've come accross a piece of code using various techniques of obfuscation and, mostly driven by curiosity, have been trying to understand the techniques it uses.
I've done some work on it, but i'm at a point where I don't understand fully what it's doing :
public $x1528 = null;
public $x153c = null;
function __construct()
{
$this->x1528 = new \StdClass();
$this->x153c = new \StdClass();
$this->x1528->x21a9 = "getSingleton";
$this->x1528->x1569 = "x1565";
$this->x1528->x1e45 = "x1e40";
$this->x153c->x3b3b = "x3b38";
$this->x1528->x16c3 = "x16c2";
$this->x1528->x1bec = "x1be8";
$this->x1528->x245a = "x2455";
$this->x1528->x1b14 = "x10d7";
$this->x153c->x36d4 = "x36d2";
$this->x1528->x24d6 = "getSingleton";
$this->x1528->x1876 = "xf0f";
$this->x1528->x2901 = "x2900";
$this->x1528->x1877 = "x1876";
$this->x153c->x335b = "x3356";
$this->x1528->x2836 = "x2833";
$this->x1528->x2119 = "x2115";
$this->x1528->x18bb = "xf3d";
$this->x153c->x349e = "x349a";
$this->x1528->x2383 = "getData";
$this->x1528->x17b1 = "x5f2";
$this->x153c->x2d06 = "xf41";
$this->x1528->x1f35 = "x1f30";
$this->x1528->x1a93 = "x1138";
$this->x1528->x1d79 = "x1d76";
$this->x1528->x1d7c = "x1d79";
$this->x153c->x3248 = "_isAllowed";
...
[it keeps going for a while...]
So it declares empty variables, generates empty objects, and then stores strings and references to other variables, but...
for example,
$this->x1528->x21a9 = "getSingleton";
What is x21a9 ? There's no reference to this anywhere, and I thought the x1528 variable was empty ? Also, is this a way of referencing the $x1528 without the $, because i've never seen this syntax before.
This is using PHP techniques I was not aware of, and this has made me very curious. Any help ?
Without seeing the entire code it's hard to tell. But basically this is just "gibberish" making it hard to read, but basic PHP nevertheless.
What is x21a9 ?
It's just a random property set on the $x1528 class. Like:
$dummyClass = new StdClass(); // Same as $this->x1528 = new \StdClass();
$dummyClass->foo = "bar"; // Same as $this->x1528->x21a9 = "getSingleton";
Now, echo $dummyClass->foo would return bar. It's just setting a property with a value, but with "cryptic" names.
I thought the x1528 variable was empty ?
It starts out empty at the beginning of the class, but then in the constructor, it's immediately set up as an instance of StdClass:
$this->x1528 = new \StdClass();
Also, is this a way of referencing the $x1528 without the $, because i've never seen this syntax before.
This is basic syntax for objects. The object itself has a $ in front of it, but the properties don't.
use my\Project\FooClass;
$obj = new FooClass(); // ok
$name = 'FooClass';
$obj2 = new $name(); // throws an error that the class wasn't found
Well, I believe the title and the example were pretty enough explanation of my question, so just - why does this throws an error, and how should I deal with this?
Sadly, this is not possible due to the way PHP imports/aliases from namespaces. This can be remedied by using literal namespace definitions, though it no doubt sucks.
As follows:
$r = "my\\Project\\FooClass";
$k = new $r();
There is a patch in the works, or at the very least, it was on PHP's bug report a couple of months back. They will hopefully do something about it.
If it bothers you, you can use class_alias() to remedy it, by the way.
try:
$obj2 = new $name;
Remove the parenthesis
Alternatively:
$obj2 = new {$name}();
Can't explain why this doesn't work. But for how to deal with it:
$name = 'FooClass';
$name = "my\\Project\\FooClass\\" . $name; // prepend namespace
$obj2 = new $name();