Re: templates - circular

"Victor Bazarov" <>
Fri, 7 Mar 2008 11:37:19 -0500
er wrote:

On Mar 6, 6:19 pm, "Victor Bazarov" <> wrote:

er wrote:

Hi all,


I have N=2 distinct pairs of objects {(x0,y0),(x1,y1)} related as

x0 -> y0
y0 -> {x1}
x1 -> y1
y1 -> {x0}

where -> represents, for example, has-a-ptr-to. Classes of objects
labeled x# and y# may have to support some operations (to safisfy
their left or right neighbors) but are of arbitrary type. So a class
for x# has to be like template<class Ty> class M_x{}, but also
template<class Tx> class M_y{},
which runs into a circular problem.

Any suggestion, please?

2) How about N>2? for example N=3,

x0 -> y0
y0 -> {x1,x2}
x1 -> y1
y1 -> {x0,x2}
x2 -> y2
y2 -> {x0,x1}

Is this homework? Even if it isn't, would you perhaps show us what
you already have?

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What I already have is a specific configuration {(M_x_fc,M_y_fc),
(M_x_fc,M_y_fc)} (see below). What i'd like to able to do is have an
arbitrary configuration, so long as the required operations are
supported. For example, M_x_fc requires that r_type support mean(),
and M_y_fc requires that l_type support x(); Please ask if still not

class M_x_fc{
void update(double);
double x()const;
typedef M_y_fc r_type;
typedef boost::shared_ptr<const r_type> ptr_const_r_type;

                               ptr_const_r_type ptr_const_r;
double _x;
void M_x_fc::update(double x_){
_x = x_;
double M_x_fc::mean()const{return ptr_const_r->mean();};

class M_y_fc{
typedef M_x_fc l_type;
typedef boost::shared_ptr<const l_type> ptr_const_l_type;
void set(ptr_const_l_type ptr_l_compl);
double mean()const;

double _rho;
double _mean;
ptr_const_l_type ptr_l_compl;
void M_y_fc::update(){
_mean = _rho*(ptr_l_compl->x());

double M_y_fc::mean()const{return _mean;};

class Config_fcfc{
typedef M_x_fc l_fc_type;
typedef M_y_fc r_fc_type;
typedef boost::shared_ptr<l_fc_type> ptr_l_fc_type;
typedef boost::shared_ptr<r_fc_type> ptr_r_fc_type;
Config_fcfc(double rho);

ptr_r_fc_type ptr_r_fc_0;
ptr_r_fc_type ptr_r_fc_1;
ptr_l_fc_type ptr_l_fc_0;
ptr_l_fc_type ptr_l_fc_1;

Config_fcfc::Config_fcfc(double rho):
ptr_r_fc_0( new r_fc_type(0,rho)),
ptr_r_fc_1( new r_fc_type(1,rho)),
ptr_l_fc_0( new l_fc_type(ptr_r_fc_0)),
ptr_l_fc_1( new l_fc_type(ptr_r_fc_1))

It's still unclear what exactly you need to do and can't.

    template<class T> class M_x;
    template<class T> class M_y;

    template<class T> class M_x {
        typedef M_y<T> r_type;

    template<class T> class M_x {
        typedef M_x<T> l_type;

Make sure you define all members _after_ both class templates
are defined, and not after _each_ class template.

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