I have a question about this passage from "Agile Web Application Development with Yii 1.1":
[b]The Yii::import method allows us to quickly include the defnition of a
class. It differs from include and require in that it is more effcient. The
class defnition being imported is actually not included, until it is referenced
for the frst time. Importing the same namespace multiple times is also
much faster than include_once and require_once. Also, it is good to
note that when referring to a class defned by the Yii Framework, we do not
need to import or include it. All core Yii classes are pre-imported.[/b]
First question, how is the include not actually made until the class is referenced? Is there a parsing of the source code done before execution?
Second question, what does it mean to import the namespace multiple times, and why is this faster than include_once?