This interface has been added in v1.3:
/**
* Applies to samplers that can share state between instances. Samplers can be
created with a
* new source of randomness that sample from the same state.
*
* @param <R> Type of the sampler.
* @since 1.3
*/
public interface SharedStateSampler<R> {
/**
* Create a new instance of the sampler with the same underlying state
using the given
* uniform random provider as the source of randomness.
*
* @param rng Generator of uniformly distributed random numbers.
* @return the sampler
*/
R withUniformRandomProvider(UniformRandomProvider rng);
}
All of the DiscreteSampler and ContinuousSampler classes have been updated to
implement SharedStateSampler.
This is the equivalent of:
/**
* Sampler that generates values of type {@code int} and can create new
instances to sample
* from the same state with a given source of randomness.
*
* @since 1.3
*/
public interface SharedStateDiscreteSampler
extends DiscreteSampler, SharedStateSampler<SharedStateDiscreteSampler> {
// Marker interface
}
If this combined marker interface is added to the library it would simplify a
lot of the code for samplers which have internal delegates to avoid casting.
With this interface they can hold a SharedStateDiscreteSampler rather than a
DiscreteSampler delegate and directly use it to create new delegates.
For example PoissonSampler code which wraps a specific implementation:
/**
* @param rng Generator of uniformly distributed random numbers.
* @param source Source to copy.
*/
private PoissonSampler(UniformRandomProvider rng,
PoissonSampler source) {
super(null);
if (source.poissonSamplerDelegate instanceof SmallMeanPoissonSampler) {
poissonSamplerDelegate =
((SmallMeanPoissonSampler)source.poissonSamplerDelegate).withUniformRandomProvider(rng);
} else {
poissonSamplerDelegate =
((LargeMeanPoissonSampler)source.poissonSamplerDelegate).withUniformRandomProvider(rng);
}
}
Becomes:
private PoissonSampler(UniformRandomProvider rng,
PoissonSampler source) {
super(null);
poissonSamplerDelegate =
source.poissonSamplerDelegate.withUniformRandomProvider(rng);
}
I propose to add:
public interface SharedStateDiscreteSampler
extends DiscreteSampler, SharedStateSampler<SharedStateDiscreteSampler> {
// Marker interface
}
public interface SharedStateContinuousSampler
extends ContinuousSampler, SharedStateSampler<SharedStateContinuousSampler>
{
// Marker interface
}
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