declaring and calling PHP object functions with period in name

Question

I'm using an API that returns different values, and I want to dynamically tell my class to run a function with the same name (so i won't need a huge switch or if/else mess).

How can I declare the object method song.pause?
How can I use the object method song.pause?
This might be an XY Problem, so is there a better way to do this? One alternative i thought of is to always call str_replace('.','_',$type) and set functions without the periods. Thoughts?

Example:

<?php
class MyClass {
    ...
    ...
    $type = "song.pause"; // This value is returned from another API I can't control

    if (property_exists('MyClass', $type)) {
        $success = $this->{$type}(); // ???
    } else {
        header("HTTP/1.1 400 Invalid type: $type);
        exit;
    }


    public function 'song.pause'() { // obviously incorrect :)
          ???
    }

scrowler · Accepted Answer · 2014-09-02 03:14:52Z

3

Given a return of song.pause, conceptually song should be the class name and pause should be the method, consider this possibility:

class MyClass {
    protected $classes = array();

    function processResponse($response) {
        // $response example is "song.pause"
        list($class, $method) = explode('.', $response);
        if(!class_exists($class)) {
            // Class doesn't exist
            die("Class name {$class} doesn't exist! Exiting...");
        }

        // Instantiate class
        $this->classes[$class] = new $class();

        if(!method_exists($this->classes[$class], $method)) {
            // Method doesn't exist within specified class
            die("Method name {$method} doesn't exist within {$class}. Exiting...");
        }

        // Call method
        $result = $this->classes[$class]->{$method}();

        return $result;
    }
}

Your logic implementation would be something like this:

class song {
    public function pause() {
        return 'foobar';
    }
}

Here's an example.

edited Sep 2, 2014 at 3:14

answered Sep 2, 2014 at 3:09

scrowler

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2 Comments

FuzzyTree Over a year ago

+1 but what's the point of keeping a copy of the object inside of $this->classes (especially since it gets overwritten)?

scrowler Over a year ago

Purely for not needing to define a property for each child class name - keep them in an array instead. No difference between that and $this->{$class} if you want to define it for each possible child.

Community · Accepted Answer · 2017-05-23 11:54:02Z

Unfortunately, what you're generally asking is not supported. From the manual:

Function names follow the same rules as other labels in PHP. A valid function name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. As a regular expression, it would be expressed thus: [a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*.

This also applies to class methods.

As the walkaround, you may follow the way that you suggested yourself:

$type = 'song.pause';
$type = str_replace('.', '_', $type);
$this->{$type}(); // will call song_pause()

OR use "dark" magic:

<?php
// header('Content-Type: text/plain; charset=utf-8');

class Test {
    function __call($method, $args){
        // do redirect to proper processing method here
        print_r($method);
        echo PHP_EOL;
        print_r($args);
    }
}

$x = new Test();
$x->{'song.pause'}(1,2,3);
?>

Shows:

song.pause           // < the method
Array                // < arguments
(
    [0] => 1
    [1] => 2
    [2] => 3
)

However, the "long" and really transparent way, which I completely agree with, is suggested by @scrowler.

John Kurlak · Accepted Answer · 2014-09-02 03:08:03Z

2

@HAL9000 is right: what you want is not supported. One potential workaround is:

Define the handlers:

$typeHandlers = array();
$typeHandlers['song.pause'] = function () {
    echo 'Pause!'; // or whatever...
};

Call the appropriate handler:

$typeHandlers[$type]();

answered Sep 2, 2014 at 3:08

John Kurlak

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