In $typemap(), the $n special variables are replaced by the appropriate
value for the type associated with the typemap calling $typemap().
The (undocumented) special variable overrides now also support
controlling what the $n special variables are replaced with from the
calling typemap, for example:
%typemap(in) std::pair<std::string, int> {
int& input_value_second = $1.second;
$typemap(in, int, 1=input_value_second);
...
}
replaces $1 in the int typemap with input_value_second instead of
whatever is the default for the target language (a variable that holds
the int value after marshalling from the target language).
This additional functionality might make it possible to replace the C++
templates used in the UTL with a much simpler system of typemaps utilising
$typemap(). See follow on commit to typemaps.c.
William S Fulton