add_action.. will work if function is empty?

Question

My Example:

function example() {
  if ($checked) echo 'true';
 }
add_action('wp_head', 'example');

now, if not $checked, will wordpress do an empty add_action or will avoid it? if do, how I can just add action if $checked is true?

janh · Accepted Answer · 2017-10-08 20:54:52Z

1

The function will run, but nothing will happen. There is a small overhead, but you shouldn't worry about it, the possible savings are minimal.

Depending on when you have $checked available, you could also do

function example() {
    echo 'true';
}
if ($checked) add_action('wp_head', 'example');

answered Oct 8, 2017 at 20:54

janh

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Thanks, will I need to Declare $checked 2 times? one inside function and second outside it?
– Jlil
Oct 8, 2017 at 21:00
1

No, just outside. If add_action is only executed if($checked), the function will never run unless $checked equals to true. Whether you do it inside or outside the function depends mostly on whether you can determine the value of $checked at template loading time where you don't know which post is requested. If you check it inside example(), get_the_ID() etc will work correctly.
– janh
Oct 8, 2017 at 21:33

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