Dynamic function name in php

Question

I would like to simplify the creation of "Custom Post Types" in WordPress as it is tedious to go through the same script and change all the custom post type name instances manually over and over.

It's quite simple to achieve by creating a variable containing the CPT name and use it everywhere it is needed. This way, All I have to do is declare the variable in the beginning of the script and that should take care of the rest.

The only issue is that, to make it work, I also need to prefix the CPT name in front of every function inside the script and it seems that using a variable in a function name is not easy or even recommended in PHP.

So how could I solve this?

Here is an example below to make it clear:

$prefix = 'news';

function news_custom_type_init()
{
    global $prefix;

    register_post_type($prefix, array(
    'labels' => array(
          'name' => $prefix,
          'singular_label' => $prefix,
          'add_new' => 'Add',
          ...
        ));

        register_taxonomy_for_object_type( 'category', $prefix );
}
add_action('init', $prefix.'_custom_type_init');

This is almost fine and could be standardized if only I could dynamically rename the function in order not to have to write the word "news" in front of it but use the "$prefix" instead.

This could have been nice but just doesn't work:

$prefix = 'news';

$functionName= $prefix."_custom_type_init";

function $functionName()
{
    global $prefix;

    register_post_type($prefix, array(
    'labels' => array(
          'name' => $prefix,
          'singular_label' => $prefix,
          'add_new' => 'Add',
          ...
        ));

        register_taxonomy_for_object_type( 'category', $prefix );
}
add_action('init', $prefix.'_custom_type_init');

Having to name manually the function kinda defeat the original purpose of my attempt (especially when the script embeds dozens of functions like this one).

What would be the best way to do this?

PS: I googled and "stackoverflowed" a lot about this but didn't find any working solution that fit my needs and doesn't generate a WordPress error message.

Thank you.

Nick Andriopoulos · Accepted Answer · 2013-02-21 14:39:26Z

20

Simple enough, here's a similar snipped form a project:

$function = $prefix . '_custom_type_init';
if(function_exists($function)) {
  $function();
}

answered Feb 21, 2013 at 14:39

Nick Andriopoulos

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3 Comments

Baylock Over a year ago

I'm not sure I made myself clear (or maybe I didn't understand your point). Your script checks to see if the function already exists and for that, the function should have been created manually in the first place, right? I'm not trying to "call" dynamically an existing function, what I'm trying to do is precisely to "create" dynamically that function. To make it simple, in my script above, I just want to erase the word "news" from anywhere but from the very first instruction and get the script to work. If I didn't get you, I'm sorry.

Nick Andriopoulos Over a year ago

If I understand correctly, you want to have a number of functions, such as "news_something" and "blog_something" etc. Then dynamically call the needed one. The code I've provided should be invoked in init() and select the function to call. If what you want is to have the same function called from several locations, I believe you need to create the functions and make them call the same function, since they need to be registered in PHP.

Baylock Over a year ago

Thank you for your help hexbot. I edited my message above to have a better understanding of my purpose with an non-working example.

sampoh · Accepted Answer · 2017-04-07 07:33:52Z

11

This is an old thread but simply use anonymous functions:

add_action('init', function() use($args) {
    //...
});

Then there is no need to declare so many functions.

edited Apr 7, 2017 at 7:33

sampoh

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answered Jul 4, 2016 at 12:42

David Vielhuber

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2 Comments

sampoh Over a year ago

A powerful technique when you are creating multiple post types using a map in a loop. This is generally a good idea if post types share some functionality but differ from data hierarchy and should not be coupled with each other as parents etc.

jgmjgm Over a year ago

There's a problem with this if people have been calling other module's functions directly. Not that you should be doing that but it can happen.

cernunnos · Accepted Answer · 2017-04-12 17:32:30Z

3

Edit (2017-04): Anonymous functions (properly implemented) are the way to go, see answer by David Vielhuber.

This answer is ill advised, as is any approach that involves code as a string, because this invites (among other things) concatenation.

Im not sure if it is advisable to use, or if it helps you, but php allows you to create "anonymous" functions :

function generateFunction ($prefix) {
    $funcname = create_function(
        '/* comma separated args here */', 
        '/* insert code as string here, using $prefix as you please */'
    );
    return $funcname;
}

$func= generateFunction ("news_custom_type_init");
$func(); // runs generated function

I am assuming add_action just calls whatever function you passed.

http://php.net/manual/en/function.create-function.php

Note: create_function will not return a function with the name you want, but the contents of the function will be under your control, and the real name of the function is not important.

edited Apr 12, 2017 at 17:32

answered Feb 21, 2013 at 14:52

cernunnos

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5 Comments

Baylock Over a year ago

Thank you cernunnos, I'm going to try this. I'm not only limited by the language here, I'm also limited by the WordPress mechanics. Hope it'll work. I'll get back to you.

Baylock Over a year ago

It doesn't work. At least not in WordPress. It genereates an error on another core page (Fatal error: Call to a member function add_rewrite_tag() on a non-object in /home/www/xxx/web/admin/wp-includes/rewrite.php). Besides, I don't believe it's the way to go as the "add_action" that triggers the function needs a string.

cernunnos Over a year ago

Thats the thing, genetareFunction returns a string, it wont have the name you expect: instead of $prefix."_customblabla" it will be something like "lamda_5", but that name will be saved onto a variable as a string and can be passed to add_action (its a valid callback, and wordpress add_action api says it accepts a valid callback). Try adding a die("i died here") in the code string to see if wordpress actually gets there (or an error_log("bla"))

sampoh Over a year ago

@cernunnos Voting down since this is no longer recommended. The create_function will be deprecated as of PHP 7.2. Use anonymous function instead. The only drawback is that you can't remove the action once hooked with an anonymous function. From PHP docs, "Relying on this function is highly discouraged."

cernunnos Over a year ago

@sampoh updated answer, you are absolutely correct to down vote

Scransom · Accepted Answer · 2017-10-27 01:00:55Z

2

I think you could use

runkit_function_add

http://php.net/manual/pl/function.runkit-function-add.php

One other available method is to use eval()

edited Oct 27, 2017 at 1:00

Scransom

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answered Oct 27, 2017 at 0:18

ryczypior

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Comments

zabatonni · Accepted Answer · 2022-10-20 13:45:38Z

2

You can use string in brackets

("function_name_{$dynamic_var}")()

answered Oct 20, 2022 at 13:45

zabatonni

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Comments

Terry Lin · Accepted Answer · 2018-07-19 15:03:29Z

1

This post is old, but PHP 7 may solve this question.

Try:

$prefix = 'news';

$functionName = $prefix . "_custom_type_init";

${$functionName} = function() use ($prefix) {

    register_post_type($prefix, array(
        'labels' => array(
            'name' => $prefix,
            'singular_label' => $prefix,
            'add_new' => 'Add'
        )
    );

    register_taxonomy_for_object_type( 'category', $prefix );
};

add_action('init', '$' . $functionName);

I think it should work for WordPress.

answered Jul 19, 2018 at 15:03

Terry Lin

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Comments

JohnG · Accepted Answer · 2020-09-03 11:53:24Z

I'm not sure any of the above actually answer the question about dynamically creating custom post types. This works for me though:

$languages = ("English", "Spanish", "French");

foreach($languages as $language):

    $example = function () use ($language) {

        $labels = array(
                'name' => __( $language . ' Posts' ),
                'singular_name' => __( $language . ' Post' )
        );

        $args = array(
   
            'labels'              => $labels,
            'hierarchical'        => false,
            'public'              => true,
            'show_ui'             => true,
            'show_in_menu'        => true,
            'show_in_nav_menus'   => true,
            'show_in_admin_bar'   => true,
            'menu_position'       => 5,
            "rewrite" => array( "slug" => $language . "_posts", "with_front" => true ),
            'capability_type'     => 'page',
         );
        register_post_type( $language . "_posts", $args );  

    };
    add_action( 'init', $example, 0 );

endforeach;

Cryptorrior · Accepted Answer · 2021-07-28 21:01:16Z

0

Dynamic function named in PHP as variable functions

https://www.php.net/manual/en/functions.variable-functions.php

as example

$functionName = function () {
    global $prefix;

    register_post_type($prefix, array(
    'labels' => array(
          'name' => $prefix,
          'singular_label' => $prefix,
          'add_new' => 'Add',
          ...
        ));

        register_taxonomy_for_object_type( 'category', $prefix );
}

you can call it by typing $functionName()

answered Jul 28, 2021 at 21:01

Cryptorrior

1196 bronze badges

Comments

Praise Dare · Accepted Answer · 2022-07-24 19:08:06Z

0

I was also looking for a way to do this, as I wanted to create a function that could make aliases for functions, just like in ruby. e.g.

function an_insanely_long_function_name($a, $b) {
    // do something with $a and $b
}

// I'll go insane if I have to type that stupidly long function name every time 😵
// Aliases to the rescue :)
define_alias('shrt_nm', 'an_insanely_long_function_name');

shrt_nm('a', 'b');

I did quite a lot of research — for like 2 mins :p — and found nothing that could help me achieve that functionality.

I was about to give up and do it all manually, but then I remembered good old "eval", my long time buddy :).

Here's what you need to do:

function define_alias($alias, $function) {
    if (function_exists($alias))
        throw new \Exception('A function named ' . $alias . ' already exists!');

    // create the function
    eval("function $alias(...\$args) { $function(...\$args); }")
}

answered Jul 24, 2022 at 19:08

Praise Dare

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1 Comment

Bachir Messaouri Over a year ago

Thanks. It's been years since I wrote this question and I have no need for an answer anymore but maybe this will help someone out there. PS: mentioning 'eval" in stack overflow is kind of bold since, most of the time, people hate it ;-)

Vitalicus · Accepted Answer · 2022-07-26 16:07:44Z

0

eval() is the simpliest method https://www.php.net/manual/en/function.eval.php

$name='new_func';
$var = eval($name."();");

function new_func(){echo "It work";}

answered Jul 26, 2022 at 16:07

Vitalicus

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