Re: Characterize parameters by type

mzdude <>
Mon, 29 Jun 2009 23:09:40 CST
On Jun 29, 5:31 pm, Rune Allnor <> wrote:

Hi all.

I have an application written in C++ that needs to be
interfaces with matlab. The interface routine needs to
take a number of untyped parameters from matlab
domain, and return a typed object to be passed to the
C++ business routine.

The parameters are:

par1 - vector of either 2 or 4 doubles
par2 - vector of 2 doubles

I would like to implement a test TestParameters that
returns an object which type depends on the combination
of the parameters:

if (par1.size() == 2)
     if (par2(1) > par2(2))
         // return object of class Case1Class
         // return object of class Case2Class}

else if (par1.size() == 4 )
     if (par2(1) > par2(2))
         // return object of class Case3Class
         // return object of class Case4Class}

     return 0;


I can't see how to wrap this into a function that can
be called from the interface routine.

Any suggestions?

A couple.
    Create a class factory that uses polymorphism
    Check out boost::any

// Warning all code untested
class Base {};

class Case1Class : public Base {};
class Case2Class : public Base {};
class Case3Class : public Base {};
class Case4Class : public Base {};

// pick the pointer type that best works for you
MyClassFactory( X const &par1, Y const &par2 )
   Base *p = 0;
   if (par1.size() == 2)
     if (par2(1) > par2(2))
       p = new Case1Class;
       p = new Case2Class;
   else if (par1.size() == 4 )
     if (par2(1) > par2(2))
       p = new Case3Class;
       p = new Case4Class;
   return p;

/////////////// OR /////////////////

struct X { int a;};
struct Y { float b;};

boost::any MyClassFactory(int a)
       return boost::any( X() );

    return boost::any( Y() );

void SomeFunct()
    boost::any b = MyClassFactory(0);

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