If you want to keep your log on the server, try using php’s error_log()
which is more flexible than just writing to files on disk. Something along the lines of:
add_filter('manage_edit-member_columns', 'set_custom_edit_member_columns');
function set_custom_edit_member_columns($columns) {
error_log(print_r($columns,true),3,__DIR__."/log.txt");
$columns['photo'] = "Photo";
return $columns;
}
OTOH, if you find the browser console more convenient, you should include a js script to console.log()
your data. Like so:
$log_msgs=array();
add_filter('manage_edit-member_columns', 'set_custom_edit_member_columns');
function set_custom_edit_member_columns($columns) {
global $log_msgs;
$log_msgs[]=json_encode($columns);
$columns['photo'] = "Photo";
return $columns;
}
function console_log_msgs()
{
global $log_msgs;
foreach($log_msgs as $msg)
echo "<script>console.log($msg);</script>";
}
add_action('wp_footer','console_log_msgs');
(didn’t test the above code, but you get the idea)