Group use declarations

PHP introduced namespaces as part of the 5.3 release. It provided a way to group related classes, interfaces, functions, and constants, thus making our code base more organized and readable. However, dealing with modern libraries usually involves a lot of verbosity in terms of numerous use statements used to import classes from various namespaces, as shown in the following example:

use Magento\Backend\Block\Widget\Grid;
use Magento\Backend\Block\Widget\Grid\Column;
use Magento\Backend\Block\Widget\Grid\Extended;

To address this verbosity, the PHP 7 release introduced the group use declarations, allowing the following syntax:

use Magento\Backend\Block\Widget\Grid;
use Magento\Backend\Block\Widget\Grid\{
  Column,
  Extended
};

Here, we condensed Column and Extend under a single declaration. We can further condense this using the following compound namespaces:

use Magento\Backend\Block\Widget\{
  Grid
  Grid\Column,
  Grid\Extended
};

The group use declarations act as a shorthand to condense use declarations, making it slightly easier to import classes, constants, and functions in a concise way. While their benefits seem somewhat marginal, their use is completely optional.