Why can't I call a (member) function from within a foreach?

Question

I'm working with a plugin called media tags...

The foreach looks as following (simplied as much as possible)

foreach($mediatags as $mediatag){
 $args = 'media_tags=animals&numberposts=10&return_type=li&size=thumbnail';
 $media_items = get_attachments_by_media_tags($args);
 echo $media_items;
};

running the exact same code outisde a foreach:

$args = 'media_tags=animals&numberposts=10&return_type=li&size=thumbnail';
 $media_items = get_attachments_by_media_tags($args);
 echo $media_items;

Works great, but when I run it inside the foreach I get the followin error:

Call to a member function get_attachments_by_media_tags() on a non-object in /home/nuagency/dev.nuagency.se/wp-content/plugins/media-tags/mediatags_template_functions.php on line 128

Heading over to line 128 in that file I see:

function get_attachments_by_media_tags($args='')
{
    global $mediatags;

    return $mediatags->get_attachments_by_media_tags($args);
}

Answer 1

You use $mediatags variable in global scope as array in your loop, and then try to use the same variable as object in your function.

You override your global $mediatags variable in your loop. Try to use following code:

foreach($new_name_for_mediatags_array as $mediatag){
 $args = 'media_tags=animals&numberposts=10&return_type=li&size=thumbnail';
 $media_items = get_attachments_by_media_tags($args);
 echo $media_items;
};