From 3f070fbea5696da23a6e5592339bab3a94079b91 Mon Sep 17 00:00:00 2001
From: "Anthony D. Blaom" <anthony.blaom@gmail.com>
Date: Mon, 4 Mar 2024 12:21:15 +1300
Subject: [PATCH 1/4] add test to catch serialization bug

oops
---
 test/core.jl | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/test/core.jl b/test/core.jl
index 4e75ead..566b5ac 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -239,5 +239,54 @@ end
     @test iteration_parameter(model) == :n
 end
 
+# define a supervised model with ephemeral `fitresult`, but which overcomes this by
+# overloading `save`/`restore`:
+thing = []
+mutable struct EphemeralRegressor <: Deterministic
+    n::Int # dummy iteration parameter
+end
+EphemeralRegressor(; n=1) = EphemeralRegressor(n)
+function MLJBase.fit(::EphemeralRegressor, verbosity, X, y)
+    # if I serialize/deserialized `thing` then `view` below changes:
+    view = objectid(thing)
+    fitresult = (thing, view, mean(y))
+    return fitresult, nothing, NamedTuple()
+end
+function MLJBase.predict(::EphemeralRegressor, fitresult, X)
+    thing, view, μ = fitresult
+    return view == objectid(thing) ? fill(μ, nrows(X)) :
+        throw(ErrorException("dead fitresult"))
+end
+MLJBase.iteration_parameter(::EphemeralRegressor) = :n
+function MLJBase.save(::EphemeralRegressor, fitresult)
+    thing, _, μ = fitresult
+    return (thing, μ)
+end
+function MLJBase.restore(::EphemeralRegressor, serialized_fitresult)
+    thing, μ = serialized_fitresult
+    view = objectid(thing)
+    return (thing, view, μ)
+end
+
+@testset "save and restore" begin
+    #https://github.com/alan-turing-institute/MLJ.jl/issues/1099
+    X, y = (; x = rand(10)), fill(42.0, 3)
+    controls = [Step(1), NumberLimit(2)]
+    imodel = IteratedModel(
+        EphemeralRegressor(42);
+        measure=l2,
+        resampling=Holdout(),
+        controls,
+    )
+    mach = machine(imodel, X, y)
+    fit!(mach, verbosity=0)
+    io = IOBuffer()
+    MLJBase.save(io, mach)
+    seekstart(io)
+    mach2 = machine(io)
+    close(io)
+    @test_broken MLJBase.predict(mach2, (; x = rand(2))) ≈ fill(42.0, 2)
+end
+
 end
 true

From e901f4a33fef286caa810eed1384b70752011fd4 Mon Sep 17 00:00:00 2001
From: "Anthony D. Blaom" <anthony.blaom@gmail.com>
Date: Mon, 4 Mar 2024 12:31:02 +1300
Subject: [PATCH 2/4] fix serialization, resolving part of MLJ.jl issue 1099

---
 src/core.jl  | 4 ++++
 test/core.jl | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/core.jl b/src/core.jl
index df5f88b..6708ab0 100644
--- a/src/core.jl
+++ b/src/core.jl
@@ -151,3 +151,7 @@ MLJBase.predict(::EitherIteratedModel, fitresult, Xnew) =
 
 MLJBase.transform(::EitherIteratedModel, fitresult, Xnew) =
     transform(fitresult, Xnew)
+
+# here `fitresult` is a trained atomic machine:
+MLJBase.save(::EitherIteratedModel, fitresult) = MLJBase.serializable(fitresult)
+MLJBase.restore(::EitherIteratedModel, fitresult) = MLJBase.restore!(fitresult)
diff --git a/test/core.jl b/test/core.jl
index 566b5ac..f7dccde 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -285,7 +285,7 @@ end
     seekstart(io)
     mach2 = machine(io)
     close(io)
-    @test_broken MLJBase.predict(mach2, (; x = rand(2))) ≈ fill(42.0, 2)
+    @test MLJBase.predict(mach2, (; x = rand(2))) ≈ fill(42.0, 2)
 end
 
 end

From 4e324106e49da4d9d00bfa5b1f1b8c475c31ebf2 Mon Sep 17 00:00:00 2001
From: "Anthony D. Blaom" <anthony.blaom@gmail.com>
Date: Mon, 4 Mar 2024 12:48:48 +1300
Subject: [PATCH 3/4] bump 0.6.1

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 797cac5..2234904 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "MLJIteration"
 uuid = "614be32b-d00c-4edb-bd02-1eb411ab5e55"
 authors = ["Anthony D. Blaom <anthony.blaom@gmail.com>"]
-version = "0.6.0"
+version = "0.6.1"
 
 [deps]
 IterationControl = "b3c1a2ee-3fec-4384-bf48-272ea71de57c"

From 4db6d5930a3ac30f7db6843694082d15666bbf81 Mon Sep 17 00:00:00 2001
From: "Anthony D. Blaom" <anthony.blaom@gmail.com>
Date: Thu, 7 Mar 2024 08:08:08 +1300
Subject: [PATCH 4/4] view -> id

---
 test/core.jl | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/test/core.jl b/test/core.jl
index f7dccde..2119da4 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -247,14 +247,14 @@ mutable struct EphemeralRegressor <: Deterministic
 end
 EphemeralRegressor(; n=1) = EphemeralRegressor(n)
 function MLJBase.fit(::EphemeralRegressor, verbosity, X, y)
-    # if I serialize/deserialized `thing` then `view` below changes:
-    view = objectid(thing)
-    fitresult = (thing, view, mean(y))
+    # if I serialize/deserialized `thing` then `id` below changes:
+    id = objectid(thing)
+    fitresult = (thing, id, mean(y))
     return fitresult, nothing, NamedTuple()
 end
 function MLJBase.predict(::EphemeralRegressor, fitresult, X)
-    thing, view, μ = fitresult
-    return view == objectid(thing) ? fill(μ, nrows(X)) :
+    thing, id, μ = fitresult
+    return id == objectid(thing) ? fill(μ, nrows(X)) :
         throw(ErrorException("dead fitresult"))
 end
 MLJBase.iteration_parameter(::EphemeralRegressor) = :n
@@ -264,8 +264,8 @@ function MLJBase.save(::EphemeralRegressor, fitresult)
 end
 function MLJBase.restore(::EphemeralRegressor, serialized_fitresult)
     thing, μ = serialized_fitresult
-    view = objectid(thing)
-    return (thing, view, μ)
+    id = objectid(thing)
+    return (thing, id, μ)
 end
 
 @testset "save and restore" begin