How to chain call functions by using a string containing that chain in PHP

Question

I have a chain call like so:

$object->getUser()->getName();

I know that I can use a string to call a function on an object:

$functionName = 'getUser';
$object->$functionName() or call_user_func(array($object, functionName))

I was wondering if it was possible to do the same for a chain call? I tried to do:

$functionName = 'getUser()->getName';
$object->functionName();

But I get an error

Method name must be a string

I guess this is because the () and -> cannot be interpreted since they are part of a string? Is there any way I can achieve this without having to do:

$function1 = getUser;
$function2 = getName;
$object->$function1()->$function2();

The aim is to get an array of functions and to chain them, in order to call this chain on the given object, e.g.:

$functions = array('getCoordinates', 'getLongitude'); // or any other chain call
$functionNames = implode('()->',$functions);
$object->$functionNames()

In your class method return the current class by doing this return $this;'. — Akar
– Akar, Commented May 19, 2015 at 8:08
Does it have to be a string in this format 'getUser()->getName'? It'd be pretty darn trivial if you "support" a more neutral format like getUser.getName. Would you need to support parameters as well? (If that's the case I'd question whether this whole endeavour is a good idea though.) — deceze
– deceze ♦, Commented May 19, 2015 at 8:17
Well, that's what you have the alterable callback function for...!? If you need further details on this you should create a new question with appropriate details. — deceze
– deceze ♦, Commented May 19, 2015 at 8:48

deceze · Accepted Answer · 2015-05-19 08:28:01Z

15

Let's start with a more neutral text format that's easy to handle:

$chain = 'getUser.getName';

And then simply reduce it:

$result = array_reduce(explode('.', $chain), function ($obj, $method) {
    return $obj->$method();
}, $object);

Note that you could even inspect the $obj to figure out whether $method is a method or a property or even an array index and return the value appropriately. See Twig for inspiration.

edited May 19, 2015 at 8:28

answered May 19, 2015 at 8:20

deceze♦

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2 Comments

Voitcus Over a year ago

Nice one, but explode can use multiple-string as a delimiter, so there is no problem with ->

deceze Over a year ago

Yes, but the goal is to start from a language-neutral expression, not PHP-code-as-string.

Wilt · Accepted Answer · 2016-06-11 07:18:41Z

1

I am trying to create a generic way of filtering objects in and array. Sometimes this filtering requires a chain call to compare specific fields with a given value.

I think that instead of inventing new solution you can use existing one like PropertyAccess Component from Symfony.

edited Jun 11, 2016 at 7:18

Wilt

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answered May 19, 2015 at 8:40

pwc

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