Version 5.0 The LEDA User Manual

2. Creation
node member da da;
introduces a variable da of this class that is not bound.
node member da da(Ptr ptr);
introduces a variable da of this class, which is bound to ptr.
3. Operations
T
void
get(const node member da& ma, const Iter& it)
returns the associated value of it for this accessor.
set(node member da& ma, const Iter& it, T val)
sets the associated value of it for this accessor to the
given value.
4. Implementation
Constant Overhead.
The instance da accesses its parameter through a pointer to member of type Ptr, which
is defined for example by typedef T Str::*Ptr.
5. Example
We have a parameterized graph G where the node information type is the following struct
type Str:
struct Str {
int x;
color col; };
We want to count the number of red nodes. Since we have the template function of
sect. 13.13 we can easily use it to do the computation:
int count_red(GRAPH G) {
node_member_da Color(&Str::col);
return count_red_t(G,Color); }