Question

I would like to understand the following code from Zenphoto’s plugin:

$plugin_is_filter = 5|ADMIN_PLUGIN|THEME_PLUGIN;

The snippet was disjointed from context. It is just about the Idea behind it.

Are 5|ADMIN_PLUGIN|THEME_PLUGIN Permissions using bitwise?

When it is useful to use?

Thanks for any hint, links.

Answer 1

Bitfields are useful when you need to provide a set of boolean options in one variable. For example, PHP lets you set your error reporting like this:

error_reporting(E_ERROR | E_WARNING | E_PARSE);

In binary, those constants have these values:

E_ERROR   0001
E_WARNING 0010
E_PARSE   0100

If you OR a set of options like that together, you’ll be able to express the settings in one field:

E_ERROR | E_WARNING | E_PARSE 0111

Then, you can check for an option being set using AND:

if ($option & E_ERROR === E_ERROR) {
    // E_ERROR is set, do something
}