wordpress get variable from empty do_action - php

Question

/* I cant change this part (plugin core files) */
function test123(){
$secret = "hoho"; //i want to get this variable
do_action('custom'); //developer didnt pass any variable here
}
/* I cant change this part (plugin core files) */
add_action('custom',function() use ( $secret ) {
echo $secret; //didn't work
});
test123();
How to get $secret value? because the developer didnt pass any variable when using do_action

Answer 1

You can use like this:
function test123() {
$secret = 'hoho';
do_action( 'custom', $secret );
}
add_action('custom',function( $secret ) {
echo $secret;
});
test123();
Hope this works!

Answer 2

Your variable is out of scope
function test123(){
$secret = "hoho"; //i want to get this variable
do_action('custom'); //developer didnt pass any variable here
} //end of function scoope
add_action('custom',function() use ( $secret ) { //<-- $secret is undefined
echo $secret; //didn't work
});
There are several ways to fix this, but I cant really say how with so little context.
You could move add_action into the function
You could make $secret global etc.
modify the do action call to send it
make it a constant
make it global (keyword)
make it a property of class that maintains it's state (static etc.)
And so on, it depends how dynamic that value needs to be. Maybe that value is a static string, maybe it only exists in your function etc.
How many times you call that function may affect defining it inside, (add/remove action).
You can test this easly:
ini_set('display_errors', 1);
error_reporting(E_ALL);
add_action('custom',function() use ( $secret ) {
echo gettype($secret); //didn't work
});
Expected output
<br />
<b>Notice</b>: Undefined variable: secret in <b>...</b> on line <b>...</b><br />
NULL
UPDATE
I can't change test123()
I sort of figured that, which is why I only gave general solutions. In any case if it's just a plain old local variable within that function, there is no way to "get" its value outside of it short of editing the function in some way. This is a PHP thing (a language thing), not a WordPress thing. It has to do with how scope is handled within the function.
It may be possible to get that data some other way, that depends what it is. For example is it stored in the DB? You may be able to access that way etc... I can't say how to do that without knowing more about what it is.
It's not impossible to edit the original right. Obviously this is not ideal, but it's possible. Some tips are never edit the original. If it's part of a theme try to do it though a child theme. If it's plugin, or child theme doesn't work for it then you can duplicate it and change it's name.
I should mention depending how it's licensed this may be against that license.
You never want to edit the original because if you update the "plugin/theme" you may completely lose your changes. If it's in a copy you can comment around you changes like this:
/* START CUSTOM CODE */
And when you update the original "plugin/theme" you can easily find where your changes where (by searching for that comment text) and work them into the new version of the "plugin/theme". Which may be as simple as coping all the files but the one you changed (if nothing changed in it) etc.
As I said this isn't ideal, but it will work. It just depends how badly you want to implement it and how willing you are to maintain it.
Please see also
https://www.php.net/manual/en/language.variables.scope.php
within user-defined functions a local function scope is introduced. Any variable used inside a function is by default limited to the local function scope