PHP How to create instance of class returned as string from method invocation

Question

How to call something like this:

$instance = new ($b->method($id))();

where method(int $id): string returns class name?

The construct above gives me a syntax error, but this is ok:

$className = $b->method($id);
$instance = new $className();

I'm just wondering if and how it can be done. I was surprised that brackets could not say that content of brackets $b->method($id) should be executed first and resulting string used to object instantiating. I probably will not use it in production code, but I'm still interested.

Possible duplicate of How to instantiate from a string class name in PHP? You probably should not use the crazy code provided there... — SpazzMarticus
– SpazzMarticus, Commented Jan 22, 2018 at 13:58
I don't think it's a duplicate. And at least it's better worded and shows more research on the issue. — Ulrich Eckhardt
– Ulrich Eckhardt, Commented Jan 22, 2018 at 14:07
What's wrong with doing the ok version? First version is quite unreadable. — lolbas
– lolbas, Commented Jan 22, 2018 at 14:09
I think you need to clarify this question: Why is it so important that you don't store the class name in a variable? That's probably the cleanest solution. If you wanted, you could write a function that takes the class name as parameter and calls new on it, but that would be much uglier still. — Ulrich Eckhardt
– Ulrich Eckhardt, Commented Jan 22, 2018 at 14:09
This simply hasn't been implemented by the AST lexer. It currently only supports simple variables. This shouldn't be too difficult to implement if you put in a feature request: github.com/php-src/php/blob/… — Jeff Puckett
– Jeff Puckett, Commented Jan 22, 2018 at 17:46

Sergi Garcés · Accepted Answer · 2018-01-26 07:43:32Z

1

This is not possible on PHP because 'new' needs a string or variable with a string. The () characters are used for aritmethic associations and for parameters on languaje constructions, and you can't assign to new the result of a call to another function.

answered Jan 26, 2018 at 7:43

Sergi Garcés

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