Question

in the code below, it has the following line

 base_list(const base_list &tmp) :memory::SqlAlloc()

base_list is a method, memory is a namespace, SqlAlloc is a class, so what does it mean when combine them together?

class base_list :public memory::SqlAlloc
{
public:
  base_list(const base_list &tmp) :memory::SqlAlloc()
  {
    elements= tmp.elements;
    first= tmp.first;
    last= elements ? tmp.last : &first;
  }

Answer 1

base_list(const base_list &tmp) :memory::SqlAlloc() 

Uses Initializer list to call constructor of class SqlAlloc inside namespace memory.

For more information on advantages of using Initializer List in C++, See this.