Re: [IMP-dev] Annoyance with current restraint design

[Daniel Russel <>]

Ben Webb wrote:
> Agreed. As we already discussed, Particle* is easier to pass from Python 
> than ParticleIndex anyway. The only downsides are that
> 1) There's no easy way to check for a 'bad' particle this way (a corrupt 
> Particle could have a pointer to the model, but the model may not have 
> the corresponding pointer to the Particle). With particle indexes of 
> course you just check whether the index is in range.
Sure we can (untested code) for Restraint.h:
 void set_model(Model* model){
   IMP_assert(particles_.empty()
              || model == particles_[0]->get_model(),
              "Model* different from Particle Model*");
   model_=model;
 }

int add_particle(Particle *p) {
   IMP_assert(p != NULL, "Can't add NULL particle");
   particles_.push_back(p);
   IMP_assert(particles_[0]->get_model() == particles_.back()->get_model(),
              "All particles in restraint must be from the same model.");
   IMP_assert(particles_.back()->get_model()
              ->get_particle(particles_.back()->get_index())
              == particles_.back(),
              "Model does not have pointer to particle.");
   IMP_assert(model_== NULL || model_==particles_.back()->get_model(),
              "Restraint model pointer and particle model pointer "
              << "don't match.");
   return particles_.size()-1;
 }

> 2) This works only as long as the model's particle storage is 
> std::vector<Particle*>. For example, we couldn't switch to 
> std::vector<Particle> because then the Particle* could change when the 
> vector is resized.
>   
True. But other things would break too if we did that, so lets not :-)