Namespaces

Before we go on to actually using a package we have installed with Composer, let's take a brief moment to review what we learned about namespaces in Chapter 5, ObjectOriented Programming. This is a similar concept to the namespaces we just referenced on the Packagist site. However, these are built into the PHP language. Namespaces have been part of PHP since version 5.3 and most, if not all, of the libraries you come across will use namespaces. Namespaces allow multiple pieces of code that would otherwise have a name collision to exist side by side. Prior to namespaces, vendors would inconveniently have to create extraordinarily long class names that were prefixed with their vendor name and usually separated by underscores to avoid naming collisions. It is highly recommended that you use namespaces in your own code to help keep things well organized and simplify references between files.

To define a namespace in a file, it must be declared at the top of a file before...