[cdunn6754]

I have been using the wiki page on RTS

https://openfoamwiki.net/index.php/O...tion_mechanism

to help work through some things. It's been very helpful but I have been stuck trying to figure out one of the code snippets for a few days now without much luck. Here is the code in question

 template<class DerivedType>
class addMrConstructorToTable
{
public:
 
    static Base New ( const dictionary& dict)
    {
        return Base(new DerivedType (dict));
    }
 
    addMrConstructorToTable
    (
        const word& lookup = DerivedType::typeName
    )
    {
        constructMrConstructorTables();
        MrConstructorTablePtr_->insert(lookup, New);
    }
 
    ~addMrConstructorToTable()
    {
        destroyMrConstructorTables();
    }
};

It is the subclass that must be added to the Base class. In the text it says that calling the constructor of the 'addMrConstructorToTable' subclass should populate the static derived constructor pointer hash table (mrConstructorTable in the example) with at function pointer to the constructor of the derivedType that addMrConstructorToTable is templated upon. I see how the addMrConstructorToTable constructor

    addMrConstructorToTable::addMrConstructorToTable
    (
        const word& lookup = DerivedType::typeName
    )
    {
        constructMrConstructorTables();
        MrConstructorTablePtr_->insert(lookup, New);
    }

would do as expected provided that New was a function pointer. So finally my question is what is this addMrConstructorToTable::New function doing? Is it even a function? When it's called in the insert function call it doesn't even have it's parameter.

Is it adding a pointer to the addMrConstructorToTable::New() function itself to the hash table by not passing the argument list in the insert call? In that case I still don't understand how a function pointer to the desired derived constructor is being returned when we later access the hash table to create a DerivedType object.

return Base(new DerivedType (dict));

It seems like it is instantiating a DerivedType object with 'new' and casting the pointer to that new object to Base? That is still not the construction function pointer I was be expecting.