[tune] Deprecate tune.function (#5601)

* remove tune function

* remove examples

* Update tune-usage.rst

python/ray/tune/examples/logging_example.py

@@ -64,7 +64,7 @@ if __name__ == "__main__":
         MyTrainableClass,
         name="hyperband_test",
         num_samples=5,
-        trial_name_creator=tune.function(trial_str_creator),
+        trial_name_creator=trial_str_creator,
         loggers=[TestLogger],
         stop={"training_iteration": 1 if args.smoke_test else 99999},
         config={

python/ray/tune/sample.py

@@ -11,9 +11,6 @@ logger = logging.getLogger(__name__)
 class sample_from(object):
     """Specify that tune should sample configuration values from this function.
 
-    The use of function arguments in tune configs must be disambiguated by
-    either wrapped the function in tune.sample_from() or tune.function().
-
     Arguments:
         func: An callable function to draw a sample from.
     """
@@ -28,27 +25,10 @@ class sample_from(object):
         return "tune.sample_from({})".format(repr(self.func))
 
 
-class function(object):
-    """Wraps `func` to make sure it is not expanded during resolution.
-
-    The use of function arguments in tune configs must be disambiguated by
-    either wrapped the function in tune.sample_from() or tune.function().
-
-    Arguments:
-        func: A function literal.
-    """
-
-    def __init__(self, func):
-        self.func = func
-
-    def __call__(self, *args, **kwargs):
-        return self.func(*args, **kwargs)
-
-    def __str__(self):
-        return "tune.function({})".format(str(self.func))
-
-    def __repr__(self):
-        return "tune.function({})".format(repr(self.func))
+def function(func):
+    logger.warn("DeprecationWarning: wrapping {} with tune.function() is no "
+                "longer needed".format(func))
+    return func
 
 
 def uniform(*args, **kwargs):

python/ray/tune/suggest/variant_generator.py

@@ -162,9 +162,7 @@ def _resolve_lambda_vars(spec, lambda_vars):
                 error = e
             except Exception:
                 raise ValueError(
-                    "Failed to evaluate expression: {}: {}".format(path, fn) +
-                    ". If you meant to pass this as a function literal, use "
-                    "tune.function() to escape it.")
+                    "Failed to evaluate expression: {}: {}".format(path, fn))
             else:
                 _assign_value(spec, path, value)
                 resolved[path] = value
@@ -207,16 +205,7 @@ def _is_resolved(v):
 
 
 def _try_resolve(v):
-    if isinstance(v, types.FunctionType):
-        raise DeprecationWarning(
-            "Function values are ambiguous in Tune "
-            "configuations. Either wrap the function with "
-            "`tune.function(func)` to specify a function literal, or "
-            "`tune.sample_from(func)` to tell Tune to "
-            "sample values from the function during variant generation: "
-            "{}".format(v))
-        return False, v
-    elif isinstance(v, sample_from):
+    if isinstance(v, sample_from):
         # Function to sample from
         return False, v.func
     elif isinstance(v, dict) and len(v) == 1 and "eval" in v:

python/ray/tune/syncer.py

@@ -15,7 +15,6 @@ try:  # py3
 except ImportError:  # py2
     from pipes import quote
 
-from ray.tune.sample import function as tune_function
 from ray.tune.error import TuneError
 from ray.tune.log_sync import log_sync_template, NodeSyncMixin
 
@@ -169,8 +168,7 @@ class CommandSyncer(BaseSyncer):
 def _get_sync_cls(sync_function):
     if not sync_function:
         return
-    if isinstance(sync_function, types.FunctionType) or isinstance(
-            sync_function, tune_function):
+    if isinstance(sync_function, types.FunctionType):
         return BaseSyncer
     elif isinstance(sync_function, str):
         return CommandSyncer

python/ray/tune/tests/test_trial_runner.py

@@ -972,8 +972,8 @@ class RunExperimentTest(unittest.TestCase):
                 "stop": {
                     "training_iteration": 1
                 },
-                "trial_name_creator": tune.function(
-                    lambda t: "{}_{}_321".format(t.trainable_name, t.trial_id))
+                "trial_name_creator":
+                    lambda t: "{}_{}_321".format(t.trainable_name, t.trial_id)
             }
         })
         self.assertEquals(
@@ -1113,7 +1113,7 @@ class TestSyncFunctionality(unittest.TestCase):
                 "training_iteration": 1
             },
             upload_dir=tmpdir2,
-            sync_to_cloud=tune.function(sync_func)).trials
+            sync_to_cloud=sync_func).trials
         test_file_path = glob.glob(os.path.join(tmpdir2, "foo", "*.json"))
         self.assertTrue(test_file_path)
         shutil.rmtree(tmpdir)
@@ -1134,7 +1134,7 @@ class TestSyncFunctionality(unittest.TestCase):
             stop={
                 "training_iteration": 1
             },
-            sync_to_driver=tune.function(sync_func_driver)).trials
+            sync_to_driver=sync_func_driver).trials
         test_file_path = os.path.join(trial.logdir, "test.log2")
         self.assertFalse(os.path.exists(test_file_path))
 
@@ -1147,7 +1147,7 @@ class TestSyncFunctionality(unittest.TestCase):
                 stop={
                     "training_iteration": 1
                 },
-                sync_to_driver=tune.function(sync_func_driver)).trials
+                sync_to_driver=sync_func_driver).trials
         test_file_path = os.path.join(trial.logdir, "test.log2")
         self.assertTrue(os.path.exists(test_file_path))
         os.remove(test_file_path)
@@ -1166,8 +1166,8 @@ class TestSyncFunctionality(unittest.TestCase):
                         "training_iteration": 1
                     },
                     "upload_dir": "test",
-                    "sync_to_driver": tune.function(sync_func),
-                    "sync_to_cloud": tune.function(sync_func)
+                    "sync_to_driver": sync_func,
+                    "sync_to_cloud": sync_func
                 }).trials
             self.assertEqual(mock_sync.call_count, 0)
 
@@ -2273,11 +2273,9 @@ class TrialRunnerTest(unittest.TestCase):
         ray.init()
         trial = Trial(
             "__fake",
-            config={
-                "callbacks": {
-                    "on_episode_start": tune.function(lambda i: i),
-                }
-            },
+            config={"callbacks": {
+                "on_episode_start": lambda i: i,
+            }},
             checkpoint_freq=1)
         tmpdir = tempfile.mkdtemp()
         runner = TrialRunner(local_checkpoint_dir=tmpdir, checkpoint_period=0)

python/ray/tune/tests/test_tune_server.py

@@ -8,7 +8,6 @@ import subprocess
 import json
 
 import ray
-from ray import tune
 from ray.rllib import _register_all
 from ray.tune.trial import Trial, Resources
 from ray.tune.web_server import TuneClient
@@ -94,11 +93,9 @@ class TuneServerSuite(unittest.TestCase):
             "__fake",
             trial_id="function_trial",
             stopping_criterion={"training_iteration": 3},
-            config={
-                "callbacks": {
-                    "on_episode_start": tune.function(lambda x: None)
-                }
-            })
+            config={"callbacks": {
+                "on_episode_start": lambda x: None
+            }})
         runner.add_trial(test_trial)
 
         for i in range(3):

python/ray/tune/trial_runner.py

@@ -11,6 +11,7 @@ import os
 import re
 import time
 import traceback
+import types
 
 import ray.cloudpickle as cloudpickle
 from ray.tune import TuneError
@@ -19,7 +20,6 @@ from ray.tune.result import (TIME_THIS_ITER_S, RESULT_DUPLICATE,
                              SHOULD_CHECKPOINT)
 from ray.tune.syncer import get_syncer
 from ray.tune.trial import Trial, Checkpoint
-from ray.tune.sample import function
 from ray.tune.schedulers import FIFOScheduler, TrialScheduler
 from ray.tune.suggest import BasicVariantGenerator
 from ray.tune.util import warn_if_slow, flatten_dict
@@ -48,7 +48,7 @@ def _find_newest_ckpt(ckpt_dir):
 
 class _TuneFunctionEncoder(json.JSONEncoder):
     def default(self, obj):
-        if isinstance(obj, function):
+        if isinstance(obj, types.FunctionType):
             return self._to_cloudpickle(obj)
         try:
             return super(_TuneFunctionEncoder, self).default(obj)