Short version:
See code

Long version:
I'm working with multi scale simulations, and the typical boundary conditions are specified as

where x-bar is the center of the representative volume, and epsilon-bar is the center of the domain.

I couldn't easily add such a boundary condition (one which changes with deforming boundary), and even for for a fixed boundary, quite tedious as you would need to add lots of boundary conditions.

So I implemented this sort of dirichlet b.c. but i came across some problems in MasterDof.
Namely this

        if ( bcptr->giveClassID() == BoundaryConditionClass ) {
            return ( BoundaryCondition * ) bcptr;
        }

where i would suggest to change the condition to bcptr->giveType() == DirichletBT.

        if ( bcptr->giveType() == DirichletBT ) {
            return ( BoundaryCondition * ) bcptr;
        }

Also, is BoundaryCondition really the appropriate type to return? I would have thought GeneralBoundaryCondition was more suitable. For now, I changed my b.c. to inherit from BoundaryCondition to avoid to much change, but things such as "prescribedvalue" are meaningless for my class (instead i have "prescribedtensor").

Edit: Something else I've found

int BoundaryCondition :: isImposed(TimeStep *tStep)
{
    // returs a value of isImposedTimeFunction, indicating whether b.c. is imposed or not
    // in given time (nonzero indicates imposed b.c.).

    if ( isImposedTimeFunction ) {
        int flag;
        flag = ( domain->giveLoadTimeFunction(isImposedTimeFunction)->evaluate(tStep, VM_Total) != 0. );
        return flag;
    } else {
        // zero value indicates default behaviour -> b.c. is imposed
        // anytime
        return 1;
    }
}

where there clearly must be a bug; isImposedTimeFunction is a boolean (although an int). only ever 0 or 1.
If anything, it should say "giveLoadTimeFunction(this->loadTimeFunction)", but i believe it should be simpler than that;

flag = this->giveLoadTimeFunction()->evaluate(tStep, VM_Total) != 0.;