Question

A point from the ISO C++ draft (n3290): 3.4.3.2/1 Namespace members

For a namespace X and name m, the namespace-qualified lookup set
S(X, m) is defined as follows: Let S`(X, m) be the set of all
declarations of m in X and the inline namespace set of X (7.3.1). If
S`(X, m) is not empty, S(X, m) is S`(X, m); otherwise, S(X, m)
is the union of S(N_i, m) for all namespaces N_i nominated by
using-directives in X and its inline namespace set.

Can somebody please explain to me this clause in plain English, translating it from this mathematical speak?

Edit:PLEASE ……….can any one provide me an example ..explaining the above point ..PLEASE ………….

Answer 1

If in the namespace X, there exists at least one declaration of the name m, then those declarations are used for the lookup set.

Otherwise, all namespaces from using directives in the namespace X are checked for declarations of the name m in the same way as described above.

Or in other words : you check the namespace X and its using directives recursively for the name m, and stop the recursion at the level where declarations for the name m are found.