Advice on understanding namespace and classes in MRF

gmax · March 1, 2024, 16:49

Hi everyone, I've read a lot of useful information on this forum and today I wanted to learn more about c++ in OpenFoam.

I'm trying to introduce variable rotation axes into MRF. I came across a syntax that I often encounter in code but that I didn't completely understand, I report the part of the code that I'm trying to understand below:

Code:

Foam::IOobject Foam::IOMRFZoneList::createIOobject
 
(
 
    const fvMesh& mesh,
 
    const word& solverName
 
) const
 
{
 
    IOobject io
 
    (
 
        "MRFProperties" + solverName,
 
        mesh.time().constant(),
 
        mesh,
 
        IOobject::MUST_READ,
 
        IOobject::NO_WRITE
 
    );
 
 
 
    if (io.typeHeaderOk<IOdictionary>(true))
 
    {
 
        Info<< "Creating MRF zone list from " << io.name() << endl;
 
 
 
        io.readOpt(IOobject::MUST_READ_IF_MODIFIED);
 
    }
 
    else
 
    {
 
        Info<< "No MRF models present" << nl << endl;
 
 
 
        io.readOpt(IOobject::NO_READ);
 
    }
 
 
 
    return io;
 
}

From what I understand, an object of type

Code:

IOobject

is created, from the

Code:

FOAM

namespace, what I don't understand is the second part

Code:

Foam::IOMRFZoneList::createIOobject

. From this writing I would say that you are describing how the createIOobject method should work.
But in reality I don't understand this exactly, why do I create an object and then specify a method of creation for that object. Maybe I'm not understanding well what this line in C++ means and for this reason I ask you if you can describe to me what this type of writing represents.

I tried to replicate this writing by creating code like this:
.H

Code:

#include<iostream>

namespaceSchim{

classBase{
public:
voidmess(){
std::cout<<" classe base"<<std::endl;

      }
voidfunc();
int a;

};

classDeri: publicBase{
public:
voidmess(){
std::cout<<" classe deri"<<std::endl;

      }

};

}

namespaceSchim{
namespacederivato {
classnnsd: publicBase{
public:
voidfunc(int );

voidmess(){
std::cout<<" classe dentro name dentro name"<<std::endl;
       }

  };

 }




}

and .C file

Code:

#include"class.H"

void Schim::derivato::nnsd::Base::func(){
    std::cout<<" sono nuovo"<<std::endl;
};

intmain(){

int a;
a =2;
Schim::Base t1;
Schim::derivato::nnsd t2;
//Schim::Base Schim::derivato::nnsd::func(int a);
t1.mess();
t1.func();
t2.mess();
t2.func(2);

return0;
}

My attempt was to create something like:

Code:

Schim::Base Schim::derivato::nnsd::func(){ some stuf}

But this didn't work, what am I doing wrong?