User guide

24-131
SystemVerilog Testbench Constructs
An extends directive for a class defines a scope in SV language.
Within this scope exist the items that modify the class definition.
These items within an extends directive for a class can be divided
into the following three categories.
• Introduction
Declaration of a new property, or the definition of a new method,
a new constraint, or a new coverage group within the extends
directive scope adds (or introduces) the new symbol into the
original class definition as a new member. Such declaration/
definition is called an introduction.
•Advice
An advice is a construct to specify code that affects the behavior
of a member method of the class by weaving the specified code
into the member method definition. This is explained in more
detail later. The advice item is said to be an advice to the affected
member method.
• Hide list:
Some items within an extends directive, such as a virtual method
introduction, or an advice to virtual method may not be
permissible within the extends directive scope depending upon
the hide permissions at the place where the item is defined. A
hide list is a construct whose placement and arguments within
the extends directive scope controls the hide permissions. There
could be multiple hide lists within an extends directive.