updates

Author: sunxd3

src/AbstractMCMC.jl

@@ -82,6 +82,8 @@ struct MCMCSerial <: AbstractMCMCEnsemble end
 
 function condition end
 
+function logdensity_and_state end
+
 include("samplingstats.jl")
 include("logging.jl")
 include("interface.jl")

src/gibbs.jl

@@ -203,16 +203,7 @@ function AbstractMCMC.step(
             logdensity_model.logdensity, conditioning_variables_values
         )
 
-        # recompute the logdensity stored in the mcmc state, because the values might have been updated in other sub-problems
-        updated_log_prob = LogDensityProblems.logdensity(cond_logdensity, sub_state)
-
-        if !hasproperty(sub_state, :logp)
-            error(
-                "$(typeof(sub_state)) does not have a `:logp` field, which is required by Gibbs sampling",
-            )
-        end
-        sub_state = BangBang.setproperty!!(sub_state, :logp, updated_log_prob)
-
+        _, sub_state = AbstractMCMC.logdensity_and_state(cond_logdensity, sub_state)
         sub_state = last(
             AbstractMCMC.step(
                 rng,

test/gibbs_example/mh.jl

@@ -9,9 +9,15 @@ struct MHTransition{T}
     params::Vector{T}
 end
 
-function AbstractMCMC.LogDensityProblems.logdensity(logdensity_function, state::MHState)
-    # recompute the logdensity, instead of using the one stored in the state
-    return AbstractMCMC.LogDensityProblems.logdensity(logdensity_function, state.params)
+function AbstractMCMC.logdensity_and_state(
+    logdensity_function, state::MHState; recompute_logp::Bool=true
+)
+    if recompute_logp
+        logp, substate = AbstractMCMC.LogDensityProblems.logdensity(logdensity_function, state.params)
+        return logp, MHState(substate.params, logp)
+    else
+        return state.logp, state
+    end
 end
 
 function Base.vec(state::MHState)