[decorators] finally-style decorators and idioms

.devcontainer/devcontainer.json

@@ -23,6 +23,7 @@
                 "bierner.markdown-preview-github-styles",
                 "bungcip.better-toml",
                 "eamodio.gitlens",
+                "joaompinto.vscode-graphviz",
                 "ms-python.python",
                 "omnilib.ufmt",
                 "redhat.vscode-yaml",

.devcontainer/py310/.devcontainer/devcontainer.json

@@ -19,11 +19,15 @@
         "vscode": {
             "extensions": [
                 "bierner.github-markdown-preview",
+                "bierner.markdown-preview-github-styles",
                 "bungcip.better-toml",
-                "streetsidesoftware.code-spell-checker",
-                "lextudio.restructuredtext",
+                "eamodio.gitlens",
+                "joaompinto.vscode-graphviz",
                 "ms-python.python",
-                "omnilib.ufmt"
+                "omnilib.ufmt",
+                "redhat.vscode-yaml",
+                "streetsidesoftware.code-spell-checker",
+                "tht13.rst-vscode"
             ]
         }
     },

.vscode/settings.json

@@ -12,10 +12,15 @@
         "behaviours",
         "bierner",
         "bungcip",
+        "epilog",
+        "graphviz",
+        "literalinclude",
+        "noodly",
         "omnilib",
         "py_trees",
         "pydot",
         "pypi",
+        "seealso",
         "ufmt",
         "usort"
     ]

CHANGELOG.rst

@@ -3,7 +3,7 @@ Release Notes
 
 Forthcoming
 -----------
-* ...
+* [decorators] finally-style decorators and idioms, `#427 <https://github.com/splintered-reality/py_trees/pull/427>`_
 
 2.2.3 (2023-02-08)
 ------------------

docs/demos.rst

@@ -147,6 +147,38 @@ py-trees-demo-eternal-guard
    :linenos:
    :caption: py_trees/demos/eternal_guard.py
 
+.. _py-trees-demo-eventually-program:
+
+py-trees-demo-eventually
+------------------------
+
+.. automodule:: py_trees.demos.eventually
+    :members:
+    :special-members:
+    :show-inheritance:
+    :synopsis: demo the eventually idiom
+
+.. literalinclude:: ../py_trees/demos/eventually.py
+   :language: python
+   :linenos:
+   :caption: py_trees/demos/eventually.py
+
+.. _py-trees-demo-eventually-swiss-program:
+
+py-trees-demo-eventually-swiss
+------------------------------
+
+.. automodule:: py_trees.demos.eventually_swiss
+    :members:
+    :special-members:
+    :show-inheritance:
+    :synopsis: demo the general purpose eventually idiom
+
+.. literalinclude:: ../py_trees/demos/eventually_swiss.py
+   :language: python
+   :linenos:
+   :caption: py_trees/demos/eventually_swiss.py
+
 .. _py-trees-demo-logging-program:
 
 py-trees-demo-logging

docs/dot/demo-eventually-swiss.dot

@@ -0,0 +1,19 @@
+digraph pastafarianism {
+ordering=out;
+graph [fontname="times-roman"];
+node [fontname="times-roman"];
+edge [fontname="times-roman"];
+"Count with Result" [fillcolor=cyan, fontcolor=black, fontsize=9, label="Count with Result", shape=octagon, style=filled];
+"Work to Success" [fillcolor=orange, fontcolor=black, fontsize=9, label="Ⓜ Work to Success", shape=box, style=filled];
+"Count with Result" -> "Work to Success";
+Counter [fillcolor=gray, fontcolor=black, fontsize=9, label=Counter, shape=ellipse, style=filled];
+"Work to Success" -> Counter;
+SetResultTrue [fillcolor=gray, fontcolor=black, fontsize=9, label=SetResultTrue, shape=ellipse, style=filled];
+"Work to Success" -> SetResultTrue;
+"On Failure" [fillcolor=orange, fontcolor=black, fontsize=9, label="Ⓜ On Failure", shape=box, style=filled];
+"Count with Result" -> "On Failure";
+SetResultFalse [fillcolor=gray, fontcolor=black, fontsize=9, label=SetResultFalse, shape=ellipse, style=filled];
+"On Failure" -> SetResultFalse;
+Failure [fillcolor=gray, fontcolor=black, fontsize=9, label=Failure, shape=ellipse, style=filled];
+"On Failure" -> Failure;
+}

docs/dot/demo-eventually.dot

@@ -0,0 +1,17 @@
+digraph pastafarianism {
+ordering=out;
+graph [fontname="times-roman"];
+node [fontname="times-roman"];
+edge [fontname="times-roman"];
+"Count and Record" [fillcolor=gold, fontcolor=black, fontsize=9, label="Count and Record\nSuccessOnOne", shape=parallelogram, style=filled];
+Counting [fillcolor=orange, fontcolor=black, fontsize=9, label="Ⓜ Counting", shape=box, style=filled];
+"Count and Record" -> Counting;
+SetCountingFlagTrue [fillcolor=gray, fontcolor=black, fontsize=9, label=SetCountingFlagTrue, shape=ellipse, style=filled];
+Counting -> SetCountingFlagTrue;
+Counter [fillcolor=gray, fontcolor=black, fontsize=9, label=Counter, shape=ellipse, style=filled];
+Counting -> Counter;
+Eventually [fillcolor=ghostwhite, fontcolor=black, fontsize=9, label=Eventually, shape=ellipse, style=filled];
+"Count and Record" -> Eventually;
+SetCountingFlagFalse [fillcolor=gray, fontcolor=black, fontsize=9, label=SetCountingFlagFalse, shape=ellipse, style=filled];
+Eventually -> SetCountingFlagFalse;
+}

docs/dot/demo-finally-single-tick.dot

@@ -0,0 +1,17 @@
+digraph pastafarianism {
+ordering=out;
+graph [fontname="times-roman"];
+node [fontname="times-roman"];
+edge [fontname="times-roman"];
+root [fillcolor=orange, fontcolor=black, fontsize=9, label="Ⓜ root", shape=box, style=filled];
+SetFlagFalse [fillcolor=gray, fontcolor=black, fontsize=9, label=SetFlagFalse, shape=ellipse, style=filled];
+root -> SetFlagFalse;
+Parallel [fillcolor=gold, fontcolor=black, fontsize=9, label="Parallel\nSuccessOnOne", shape=parallelogram, style=filled];
+root -> Parallel;
+Counter [fillcolor=gray, fontcolor=black, fontsize=9, label=Counter, shape=ellipse, style=filled];
+Parallel -> Counter;
+Finally [fillcolor=ghostwhite, fontcolor=black, fontsize=9, label=Finally, shape=ellipse, style=filled];
+Parallel -> Finally;
+SetFlagTrue [fillcolor=gray, fontcolor=black, fontsize=9, label=SetFlagTrue, shape=ellipse, style=filled];
+Finally -> SetFlagTrue;
+}

docs/dot/eventually-swiss.dot

@@ -0,0 +1,19 @@
+digraph pastafarianism {
+ordering=out;
+graph [fontname="times-roman"];
+node [fontname="times-roman"];
+edge [fontname="times-roman"];
+"Eventually (Swiss)" [fillcolor=cyan, fontcolor=black, fontsize=9, label="Eventually (Swiss)", shape=octagon, style=filled];
+"Work to Success" [fillcolor=orange, fontcolor=black, fontsize=9, label="Ⓜ Work to Success", shape=box, style=filled];
+"Eventually (Swiss)" -> "Work to Success";
+Worker [fillcolor=gray, fontcolor=black, fontsize=9, label=Worker, shape=ellipse, style=filled];
+"Work to Success" -> Worker;
+"On Success" [fillcolor=gray, fontcolor=black, fontsize=9, label="On Success", shape=ellipse, style=filled];
+"Work to Success" -> "On Success";
+"On Failure" [fillcolor=orange, fontcolor=black, fontsize=9, label="Ⓜ On Failure", shape=box, style=filled];
+"Eventually (Swiss)" -> "On Failure";
+"On Failure*" [fillcolor=gray, fontcolor=black, fontsize=9, label="On Failure*", shape=ellipse, style=filled];
+"On Failure" -> "On Failure*";
+Failure [fillcolor=gray, fontcolor=black, fontsize=9, label=Failure, shape=ellipse, style=filled];
+"On Failure" -> Failure;
+}

docs/dot/eventually.dot

@@ -0,0 +1,13 @@
+digraph pastafarianism {
+ordering=out;
+graph [fontname="times-roman"];
+node [fontname="times-roman"];
+edge [fontname="times-roman"];
+Eventually [fillcolor=gold, fontcolor=black, fontsize=9, label="Eventually\nSuccessOnOne", shape=parallelogram, style=filled];
+Worker [fillcolor=gray, fontcolor=black, fontsize=9, label=Worker, shape=ellipse, style=filled];
+Eventually -> Worker;
+"Eventually*" [fillcolor=ghostwhite, fontcolor=black, fontsize=9, label="Eventually*", shape=ellipse, style=filled];
+Eventually -> "Eventually*";
+"On Completion" [fillcolor=gray, fontcolor=black, fontsize=9, label="On Completion", shape=ellipse, style=filled];
+"Eventually*" -> "On Completion";
+}

docs/examples/eventually.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import py_trees
+
+if __name__ == "__main__":
+    worker = py_trees.behaviours.Success(name="Worker")
+    on_completion = py_trees.behaviours.Success(name="On Completion")
+    root = py_trees.idioms.eventually(
+        name="Eventually",
+        worker=worker,
+        on_completion=on_completion,
+    )
+    py_trees.display.render_dot_tree(
+        root, py_trees.common.string_to_visibility_level("all")
+    )

docs/examples/eventually_swiss.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import py_trees
+
+if __name__ == "__main__":
+    worker = py_trees.behaviours.Success(name="Worker")
+    on_failure = py_trees.behaviours.Success(name="On Failure")
+    on_success = py_trees.behaviours.Success(name="On Success")
+    root = py_trees.idioms.eventually_swiss(
+        name="Eventually (Swiss)",
+        workers=[worker],
+        on_failure=on_failure,
+        on_success=on_success,
+    )
+    py_trees.display.render_dot_tree(
+        root, py_trees.common.string_to_visibility_level("all")
+    )

docs/idioms.rst

@@ -43,3 +43,15 @@ Pickup Where You left Off
 
 .. automethod:: py_trees.idioms.pick_up_where_you_left_off
     :noindex:
+
+Eventually
+----------
+
+.. automethod:: py_trees.idioms.eventually
+    :noindex:
+
+Eventually - Swiss Variant
+--------------------------
+
+.. automethod:: py_trees.idioms.eventually_swiss
+    :noindex:

py_trees/behaviour.py

@@ -344,7 +344,7 @@ def iterate(self, direct_descendants: bool = False) -> typing.Iterator[Behaviour
                 yield child
         yield self
 
-    # TODO: better type refinement of 'viso=itor'
+    # TODO: better type refinement of 'visitor'
     def visit(self, visitor: typing.Any) -> None:
         """
         Introspect on this behaviour with a visitor.

py_trees/behaviours.py

@@ -280,6 +280,7 @@ def update(self) -> common.Status:
             :data:`~py_trees.common.Status.RUNNING` while not expired, the given completion status otherwise
         """
         self.counter += 1
+        self.feedback_message = f"count: {self.counter}"
         if self.counter <= self.duration:
             return common.Status.RUNNING
         else:

py_trees/decorators.py

@@ -38,6 +38,7 @@
 * :class:`py_trees.decorators.EternalGuard`
 * :class:`py_trees.decorators.Inverter`
 * :class:`py_trees.decorators.OneShot`
+* :class:`py_trees.decorators.OnTerminate`
 * :class:`py_trees.decorators.Repeat`
 * :class:`py_trees.decorators.Retry`
 * :class:`py_trees.decorators.StatusToBlackboard`
@@ -920,3 +921,64 @@ def update(self) -> common.Status:
             the behaviour's new status :class:`~py_trees.common.Status`
         """
         return self.decorated.status
+
+
+class OnTerminate(Decorator):
+    """
+    Trigger the child for a single tick on :meth:`terminate`.
+
+    Always return :data:`~py_trees.common.Status.RUNNING` and on
+    on :meth:`terminate`, call the child's
+    :meth:`~py_trees.behaviour.Behaviour.update` method, once.
+
+    This is useful to cleanup, restore a context switch or to
+    implement a finally-like behaviour.
+
+    .. seealso:: :meth:`py_trees.idioms.eventually`
+    """
+
+    def __init__(self, name: str, child: behaviour.Behaviour):
+        """
+        Initialise with the standard decorator arguments.
+
+        Args:
+            name: the decorator name
+            child: the child to be decorated
+        """
+        super(OnTerminate, self).__init__(name=name, child=child)
+
+    def tick(self) -> typing.Iterator[behaviour.Behaviour]:
+        """
+        Bypass the child when ticking.
+
+        Yields:
+            a reference to itself
+        """
+        self.logger.debug(f"{self.__class__.__name__}.tick()")
+        self.status = self.update()
+        yield self
+
+    def update(self) -> common.Status:
+        """
+        Return with :data:`~py_trees.common.Status.RUNNING`.
+
+        Returns:
+            the behaviour's new status :class:`~py_trees.common.Status`
+        """
+        return common.Status.RUNNING
+
+    def terminate(self, new_status: common.Status) -> None:
+        """Tick the child behaviour once."""
+        self.logger.debug(
+            "{}.terminate({})".format(
+                self.__class__.__name__,
+                "{}->{}".format(self.status, new_status)
+                if self.status != new_status
+                else f"{new_status}",
+            )
+        )
+        if new_status == common.Status.INVALID:
+            self.decorated.tick_once()
+            # Do not need to stop the child here - this method
+            # is only called by Decorator.stop() which will handle
+            # that responsibility immediately after this method returns.

py_trees/demos/__init__.py

@@ -21,6 +21,8 @@
 from . import display_modes  # usort:skip  # noqa: F401
 from . import dot_graphs  # usort:skip  # noqa: F401
 from . import either_or  # usort:skip  # noqa: F401
+from . import eventually  # usort:skip  # noqa: F401
+from . import eventually_swiss  # usort:skip  # noqa: F401
 from . import lifecycle  # usort:skip  # noqa: F401
 from . import selector  # usort:skip  # noqa: F401
 from . import sequence  # usort:skip  # noqa: F401