From f478e0cfb76719f26c1797c65ec5b34eed892c44 Mon Sep 17 00:00:00 2001
From: Niels Wouda <N-Wouda@users.noreply.github.com>
Date: Mon, 16 May 2022 16:58:25 +0200
Subject: [PATCH] Fix bug where on_best did not receive iterate() kwargs (#63)

* Fix bug where on_best did not receive iterate() kwargs

* Bump version
---
 alns/ALNS.py            |  8 ++++++--
 alns/tests/test_alns.py | 19 +++++++++++++++++++
 pyproject.toml          |  2 +-
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/alns/ALNS.py b/alns/ALNS.py
index cec8f28..6664109 100644
--- a/alns/ALNS.py
+++ b/alns/ALNS.py
@@ -176,7 +176,11 @@ class of vehicle routing problems with backhauls. *European Journal of
             destroyed = d_operator(curr, self._rnd_state, **kwargs)
             cand = r_operator(destroyed, self._rnd_state, **kwargs)
 
-            best, curr, s_idx = self._consider_candidate(crit, best, curr, cand)
+            best, curr, s_idx = self._eval_cand(crit,
+                                                best,
+                                                curr,
+                                                cand,
+                                                **kwargs)
 
             weight_scheme.update_weights(d_idx, r_idx, s_idx)
 
@@ -201,7 +205,7 @@ def on_best(self, func: _OperatorType):
         """
         self._on_best = func
 
-    def _consider_candidate(
+    def _eval_cand(
             self,
             crit: AcceptanceCriterion,
             best: State,
diff --git a/alns/tests/test_alns.py b/alns/tests/test_alns.py
index 32cf16c..714f6e9 100644
--- a/alns/tests/test_alns.py
+++ b/alns/tests/test_alns.py
@@ -192,6 +192,25 @@ def test_operator(state, rnd, item):
     alns.iterate(init_sol, weights, HillClimbing(), 10, item=orig_item)
 
 
+def test_bugfix_pass_kwargs_to_on_best():
+    """
+    Exercises a bug where the on_best callback did not receive the kwargs passed
+    to iterate().
+    """
+    def test_operator(state, rnd, item):
+        assert_(item is orig_item)
+        return Zero()  # better, so on_best is triggered
+
+    alns = get_alns_instance([lambda state, rnd, item: state], [test_operator])
+    alns.on_best(lambda state, rnd, item: state)
+
+    init_sol = One()
+    weights = SimpleWeights([1, 1, 1, 1], 1, 1, .5)
+    orig_item = object()
+
+    alns.iterate(init_sol, weights, HillClimbing(), 10, item=orig_item)
+
+
 # EXAMPLES ---------------------------------------------------------------------
 
 
diff --git a/pyproject.toml b/pyproject.toml
index f4c0793..544ef2c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "alns"
-version = "2.1.1"
+version = "2.1.2"
 description = "A flexible implementation of the adaptive large neighbourhood search (ALNS) algorithm."
 authors = ["Niels Wouda <n.wouda@apium.nl>"]
 license = "MIT"