Class definitions can become very long with a lot of lines between class and endclass. This makes it difficult to understand what all functions and variables exist within the class because each function and task occupy quite a lot of lines.
Using extern qualifier in method declaration indicates that the implementation is done outside the body of this class.
Example
class ABC;
// Let this function be declared here and defined later
// by "extern" qualifier
extern function void display();
endclass
// Outside the class body, we have the implementation of the
// function declared as "extern"
function void ABC::display();
$display ("Hello world");
endfunction
module tb;
// Lets simply create a class object and call the display method
initial begin
ABC abc = new();
abc.display();
end
endmodule
Simulation Log
ncsim> run
Hello world
ncsim: *W,RNQUIE: Simulation is complete.
