Why does BGL use friend instead of member functions?

From: Louis Lavery (Louis_at_[hidden])
Date: 2002-08-11 10:02:51

Hi,

   It appears, to me, that the boost graph classes use friend functions
and apposed to member functions.
What are the reasons for this design decision (I like it) and why is the
graph passed as the last argument?

Thanks,

Louis.

PS. Great graph - great book.