nicer repr for Cluster object

Author: minrk

ipyparallel/cluster/cluster.py

@@ -7,6 +7,7 @@
 import asyncio
 import inspect
 import logging
+import os
 import random
 import socket
 import string
@@ -24,9 +25,7 @@
 from traitlets import Float
 from traitlets import Integer
 from traitlets import List
-from traitlets import Type
 from traitlets import Unicode
-from traitlets import validate
 from traitlets.config import LoggingConfigurable
 
 from . import launcher
@@ -106,7 +105,7 @@ def _default_profile_dir(self):
         If you are using one of IPython's builtin launchers, you can specify just the
         prefix, e.g:
 
-            c.IPClusterStart.controller_launcher_class = 'SSH'
+            c.Cluster.controller_launcher_class = 'SSH'
 
         or:
 
@@ -145,7 +144,7 @@ def _default_profile_dir(self):
         If you are using one of IPython's builtin launchers, you can specify just the
         prefix, e.g:
 
-            c.IPClusterEngines.engine_launcher_class = 'SSH'
+            c.Cluster.engine_launcher_class = 'SSH'
 
         or:
 
@@ -206,6 +205,26 @@ def _default_log(self):
     _controller = Any()
     _engine_sets = Dict()
 
+    def __repr__(self):
+        profile_dir = self.profile_dir
+        home_dir = os.path.expanduser("~")
+        if profile_dir.startswith(home_dir + os.path.sep):
+            # truncate $HOME/. -> ~/...
+            profile_dir = "~" + profile_dir[len(home_dir) :]
+
+        fields = {
+            "cluster_id": repr(self.cluster_id),
+            "profile_dir": repr(profile_dir),
+        }
+        if self._controller:
+            fields["controller"] = "<running>"
+        if self._engine_sets:
+            fields["engine_sets"] = list(self._engine_sets)
+
+        fields_str = ', '.join(f"{key}={value}" for key, value in fields.items())
+
+        return f"<{self.__class__.__name__}({fields_str})>"
+
     @classmethod
     def from_json(self, json_dict):
         """Construct a Cluster from serialized state"""

ipyparallel/tests/test_cluster.py

@@ -143,3 +143,18 @@ def test_sync_with(Cluster):
 def test_cluster_abbreviations(classname, expected_class):
     c = cluster.Cluster(engine_launcher_class=classname)
     assert c.engine_launcher_class is expected_class
+
+
+async def test_cluster_repr(Cluster):
+    c = Cluster(cluster_id="test", profile_dir='/tmp')
+    assert repr(c) == "<Cluster(cluster_id='test', profile_dir='/tmp')>"
+    await c.start_controller()
+    assert (
+        repr(c)
+        == "<Cluster(cluster_id='test', profile_dir='/tmp', controller=<running>)>"
+    )
+    await c.start_engines(1, 'engineid')
+    assert (
+        repr(c)
+        == "<Cluster(cluster_id='test', profile_dir='/tmp', controller=<running>, engine_sets=['engineid'])>"
+    )