Activity api

docs/index.rst

@@ -63,7 +63,7 @@ All hard-to-use functionality is automatically scoped and managed, making it nat
 .. code:: python3
 
    # scoping is a builtin concept of usim
-   async with out(time >= 3000) as scope:
+   async with until(time >= 3000) as scope:
       # complex tools are automatically managed
       async for message in stream:
          scope.do(handle(message))

docs/source/glossary.rst

@@ -2,18 +2,23 @@
 Glossary of Terms
 =================
 
+.. Using references in the glossary itself:
+   When mentioning other items, always reference them.
+   When mentioning the current item, never reference it.
+
 
 .. glossary::
 
     Activity
-        Ongoing action that drives forward a simulation - either through time or events.
-        Activities may be suspended and resumed as desired, or interrupted involuntarily.
+        Ongoing action that drives forward a simulation - either through :term:`time` or :term:`events <event>`.
+        Activities may be :term:`suspended <Suspension>` and resumed as desired, or interrupted involuntarily.
 
     Time
         Representation of the progression of a simulation.
         Whereas the unit of time is arbitrary, its value always grows.
 
-        Time may only pass while all :term:`activities <Activity>` are *suspended*.
+        Time may only pass while all :term:`activities <Activity>`
+        are :term:`suspended <Suspension>` until a later time, not :term:`turn`.
         An :term:`activity` may actively wait for the progression of time,
         or implicitly delay until an event happens at a future point in time.
 
@@ -23,10 +28,30 @@ Glossary of Terms
     Event
         A well-defined occurrence at a specific point in :term:`time`.
         Events may occur
-        as result of activities ("dinner is done"),
+        as result of activities ("when dinner is done"),
         as time passes ("after 20 time units"),
         or
         at predefined points in time ("at 2000 time units"),
 
     Notification
         Information sent to an :term:`activity`, usually in response to an :term:`event`.
+        Notifications are only received when the :term:`activity`
+        is :term:`suspended <Suspension>`, i.e. at an ``await``, ``async for`` or ``async with``.
+
+    Postponement
+        :term:`Suspension` of an :term:`activity` until a later :term:`turn` at the same :term:`time`.
+        When an :term:`activity` is postponed, :term:`notifications <Notification>` may be received
+        and other :term:`activities <Activity>` may run but :term:`time` does not advance.
+
+        :note: μSim guarantees that all its primitives postpone on asynchronous operations.
+               This ensures that activities are reliably and deterministically interwoven.
+
+    Suspension
+        Pause the execution of an :term:`activity`,
+        allowing other :term:`activities <activity>` or :term:`time` to advance.
+        A suspended activity is only resumed when it receives a :term:`notification`.
+
+        Suspension can only occur as part of asynchronous statements:
+        waiting for the target of an ``await`` statement,
+        fetching the next item of an ``async for`` statement,
+        and entering/exiting an ``async with`` block.

docs/source/tutorial/03_scopes.rst

@@ -36,7 +36,7 @@ We again use ``usim.time`` to track and influence the progression of our simulat
     ...         await (time + 1)                       # 3
     ...         drivers.do(deliver_one(3))
     ...         print('Sent deliveries at', time.now)  # 4.1
-    ...     print('-- Done deliveries at', time.now)      # 4.2
+    ...     print('-- Done deliveries at', time.now)   # 4.2
 
 Scopes can be difficult because they are inherently about doing several things at once.
 It helps to step through individual points of notice:

docs/source/tutorial/04_cancel_scope.rst

@@ -0,0 +1,21 @@
+
+Interlude 01: Interrupting Scopes
+---------------------------------
+
+.. code:: python3
+
+    >>> from usim import time, until
+    >>>
+    >>> async def deliver_one(which):
+    ...     print('Delivering', which, 'at', time.now)
+    ...     await (time + 5)
+    ...     print('Delivered', which, 'at', time.now)
+    >>>
+    >>> async def deliver_all(count=3):
+    ...     print('-- Start deliveries at', time.now)
+    ...     async with until(time + 10) as deliveries:   # 1
+    ...         for delivery in range(count):          # 2
+    ...             deliveries.do(deliver_one(delivery))
+    ...             await (time + 3)
+    ...         print('Sent deliveries at', time.now)  # 4.1
+    ...     print('-- Done deliveries at', time.now)   # 4.2

usim/__init__.py

@@ -5,14 +5,14 @@
 from ._primitives.timing import Time, Eternity, Instant, each
 from ._primitives.flag import Flag
 from ._primitives.locks import Lock
-from ._primitives.context import until, Scope, VolatileActivityExit
-from ._primitives.activity import ActivityCancelled, ActivityState
+from ._primitives.context import until, Scope, VolatileTaskExit
+from ._primitives.task import TaskCancelled, TaskState
 
 
 __all__ = [
     'run',
     'time', 'eternity', 'instant', 'each',
-    'until', 'Scope', 'ActivityCancelled', 'VolatileActivityExit', 'ActivityState',
+    'until', 'Scope', 'TaskCancelled', 'VolatileTaskExit', 'TaskState',
     'Flag', 'Lock',
 ]
 

usim/_primitives/condition.py

@@ -10,14 +10,48 @@
 
 class Condition(Notification):
     """
-    A logical condition that triggers when ``True``
+    An asynchronous logical condition
+
+    Every :py:class:`~.Condition` can be used both in an
+    asynchronous *and* boolean context.
+    In an asynchronous context,
+    such as ``await``,
+    a :py:class:`~.Condition` triggers when the :py:class:`~.Condition` becomes :py:const:`True`.
+    In a boolean context,
+    such as ``if``,
+    a :py:class:`~.Condition` provides its current boolean value.
 
     .. code:: python
 
+        if condition:    # resume with current value
+            print(condition, 'is met')
+        else:
+            print(condition, 'is not met')
+
         await condition  # resume when condition is True
 
-        async with until(condition):  # abort if condition becomes False
+        async with until(condition):  # interrupt when condition is True
             ...
+
+    Every :py:class:`~.Condition` supports the bitwise operators
+    ``~a`` (not),
+    ``a & b`` (and), and
+    ``a | b`` (or)
+    to derive a new :py:class:`~.Condition`.
+    While it is possible to use the boolean operators
+    ``not``, ``and``, and ``or``,
+    they immediately evaluate any :py:class:`~.Condition` in a boolean context.
+
+    .. code:: python
+
+        await (a & b)   # resume when both a and b are True
+        await (a | b)   # resume when one of a or b are True
+        await (a & ~b)  # resume when a is True and b is False
+
+        c = a & b  # derive new Condition...
+        await c    # that can be awaited
+
+        d = a and b  # force boolean evaluation
     """
     __slots__ = ()
 
@@ -88,7 +122,11 @@ def __repr__(self):
 
 
 class All(Connective):
-    """Logical AND of all sub-conditions"""
+    """
+    Logical AND of all sub-conditions
+
+    The expression ``a & b & c`` is equivalent to ``All(a, b, c)``.
+    """
     __slots__ = ()
 
     def __bool__(self):
@@ -102,7 +140,11 @@ def __str__(self):
 
 
 class Any(Connective):
-    """Logical OR of all sub-conditions"""
+    """
+    Logical OR of all sub-conditions
+
+    The expression ``a | b | c`` is equivalent to ``Any(a, b, c)``.
+    """
     __slots__ = ()
 
     def __bool__(self):