updated from Atlas

15-context-mngr/mirror.py

@@ -15,6 +15,8 @@ While active, the context manager reverses text output to
     YKCOWREBBAJ
     >>> what  # <4>
     'JABBERWOCKY'
+    >>> print('Back to normal.')  # <5>
+    Back to normal.
 
 # END MIRROR_DEMO_1
 

16-coroutine/coroaverager0.py

@@ -1,7 +1,7 @@
-# BEGIN CORO_AVERAGER
 """
 A coroutine to compute a running average
 
+# BEGIN CORO_AVERAGER_TEST
     >>> coro_avg = averager()  # <1>
     >>> next(coro_avg)  # <2>
     >>> coro_avg.send(10)  # <3>
@@ -11,14 +11,17 @@ A coroutine to compute a running average
     >>> coro_avg.send(5)
     15.0
 
+# END CORO_AVERAGER_TEST
+
 """
 
+# BEGIN CORO_AVERAGER
 def averager():
     total = 0.0
     count = 0
     average = None
-    while True:
-        term = yield average  # <4>
+    while True:  # <1>
+        term = yield average  # <2>
         total += term
         count += 1
         average = total/count

16-coroutine/coroaverager2.py

@@ -6,8 +6,8 @@ Testing ``averager`` by itself::
 # BEGIN RETURNING_AVERAGER_DEMO1
 
     >>> coro_avg = averager()
-    >>> next(coro_avg)  # <1>
-    >>> coro_avg.send(10)
+    >>> next(coro_avg)
+    >>> coro_avg.send(10)  # <1>
     >>> coro_avg.send(30)
     >>> coro_avg.send(6.5)
     >>> coro_avg.send(None)  # <2>
@@ -58,4 +58,4 @@ def averager():
         count += 1
         average = total/count
     return Result(count, average)  # <2>
-# END RETURNING_AVERAGER
+# END RETURNING_AVERAGER

16-coroutine/coroaverager3.py

@@ -75,7 +75,7 @@ def main(data):  # <8>
         next(group)  # <10>
         for value in values:
             group.send(value)  # <11>
-        group.send(None)  # <12>
+        group.send(None)  # important! <12>
 
     # print(results)  # uncomment to debug
     report(results)

16-coroutine/taxi_sim.py

@@ -0,0 +1,203 @@
+
+"""
+Taxi simulator
+==============
+
+Driving a taxi from the console::
+
+    >>> from taxi_sim import taxi_process
+    >>> taxi = taxi_process(ident=13, trips=2, start_time=0)
+    >>> next(taxi)
+    Event(time=0, proc=13, action='leave garage')
+    >>> taxi.send(_.time + 7)
+    Event(time=7, proc=13, action='pick up passenger')
+    >>> taxi.send(_.time + 23)
+    Event(time=30, proc=13, action='drop off passenger')
+    >>> taxi.send(_.time + 5)
+    Event(time=35, proc=13, action='pick up passenger')
+    >>> taxi.send(_.time + 48)
+    Event(time=83, proc=13, action='drop off passenger')
+    >>> taxi.send(_.time + 1)
+    Event(time=84, proc=13, action='going home')
+    >>> taxi.send(_.time + 10)
+    Traceback (most recent call last):
+      File "<stdin>", line 1, in <module>
+    StopIteration
+
+Sample run with two cars, random seed 10. This is a valid doctest::
+
+    >>> main(num_taxis=2, seed=10)
+    taxi: 0  Event(time=0, proc=0, action='leave garage')
+    taxi: 0  Event(time=5, proc=0, action='pick up passenger')
+    taxi: 1     Event(time=5, proc=1, action='leave garage')
+    taxi: 1     Event(time=10, proc=1, action='pick up passenger')
+    taxi: 1     Event(time=15, proc=1, action='drop off passenger')
+    taxi: 0  Event(time=17, proc=0, action='drop off passenger')
+    taxi: 1     Event(time=24, proc=1, action='pick up passenger')
+    taxi: 0  Event(time=26, proc=0, action='pick up passenger')
+    taxi: 0  Event(time=30, proc=0, action='drop off passenger')
+    taxi: 0  Event(time=34, proc=0, action='going home')
+    taxi: 1     Event(time=46, proc=1, action='drop off passenger')
+    taxi: 1     Event(time=48, proc=1, action='pick up passenger')
+    taxi: 1     Event(time=110, proc=1, action='drop off passenger')
+    taxi: 1     Event(time=139, proc=1, action='pick up passenger')
+    taxi: 1     Event(time=140, proc=1, action='drop off passenger')
+    taxi: 1     Event(time=150, proc=1, action='going home')
+    *** end of events ***
+
+See longer sample run at the end of this module.
+
+"""
+
+import random
+import collections
+import queue
+import argparse
+import time
+
+DEFAULT_NUMBER_OF_TAXIS = 3
+DEFAULT_END_TIME = 180
+SEARCH_DURATION = 5
+TRIP_DURATION = 20
+DEPARTURE_INTERVAL = 5
+
+Event = collections.namedtuple('Event', 'time proc action')
+
+
+# BEGIN TAXI_PROCESS
+def taxi_process(ident, trips, start_time=0):  # <1>
+    """Yield to simulator issuing event at each state change"""
+    time = yield Event(start_time, ident, 'leave garage')  # <2>
+    for i in range(trips):  # <3>
+        time = yield Event(time, ident, 'pick up passenger')  # <4>
+        time = yield Event(time, ident, 'drop off passenger')  # <5>
+
+    yield Event(time, ident, 'going home')  # <6>
+    # end of taxi process # <7>
+# END TAXI_PROCESS
+
+
+# BEGIN TAXI_SIMULATOR
+class Simulator:
+
+    def __init__(self, procs_map):
+        self.events = queue.PriorityQueue()
+        self.procs = dict(procs_map)
+
+    def run(self, end_time):  # <1>
+        """Schedule and display events until time is up"""
+        # schedule the first event for each cab
+        for _, proc in sorted(self.procs.items()):  # <2>
+            first_event = next(proc)  # <3>
+            self.events.put(first_event)  # <4>
+
+        # main loop of the simulation
+        sim_time = 0  # <5>
+        while sim_time < end_time:  # <6>
+            if self.events.empty():  # <7>
+                print('*** end of events ***')
+                break
+
+            current_event = self.events.get()  # <8>
+            sim_time, proc_id, previous_action = current_event  # <9>
+            print('taxi:', proc_id, proc_id * '   ', current_event)  # <10>
+            active_proc = self.procs[proc_id]  # <11>
+            next_time = sim_time + compute_duration(previous_action)  # <12>
+            try:
+                next_event = active_proc.send(next_time)  # <13>
+            except StopIteration:
+                del self.procs[proc_id]  # <14>
+            else:
+                self.events.put(next_event)  # <15>
+        else:  # <16>
+            msg = '*** end of simulation time: {} events pending ***'
+            print(msg.format(self.events.qsize()))
+# END TAXI_SIMULATOR
+
+
+def compute_duration(previous_action):
+    """Compute action duration using exponential distribution"""
+    if previous_action in ['leave garage', 'drop off passenger']:
+        # new state is prowling
+        interval = SEARCH_DURATION
+    elif previous_action == 'pick up passenger':
+        # new state is trip
+        interval = TRIP_DURATION
+    elif previous_action == 'going home':
+        interval = 1
+    else:
+        raise ValueError('Unknown previous_action: %s' % previous_action)
+    return int(random.expovariate(1/interval)) + 1
+
+
+def main(end_time=DEFAULT_END_TIME, num_taxis=DEFAULT_NUMBER_OF_TAXIS,
+         seed=None):
+    """Initialize random generator, build procs and run simulation"""
+    if seed is not None:
+        random.seed(seed)  # get reproducible results
+
+    taxis = {i: taxi_process(i, (i+1)*2, i*DEPARTURE_INTERVAL)
+             for i in range(num_taxis)}
+    sim = Simulator(taxis)
+    sim.run(end_time)
+
+
+if __name__ == '__main__':
+
+    parser = argparse.ArgumentParser(
+                        description='Taxi fleet simulator.')
+    parser.add_argument('-e', '--end-time', type=int,
+                        default=DEFAULT_END_TIME,
+                        help='simulation end time; default = %s'
+                        % DEFAULT_END_TIME)
+    parser.add_argument('-t', '--taxis', type=int,
+                        default=DEFAULT_NUMBER_OF_TAXIS,
+                        help='number of taxis running; default = %s'
+                        % DEFAULT_NUMBER_OF_TAXIS)
+    parser.add_argument('-s', '--seed', type=int, default=None,
+                        help='random generator seed (for testing)')
+
+    args = parser.parse_args()
+    main(args.end_time, args.taxis, args.seed)
+
+
+"""
+
+Sample run from the command line, seed=3, maximum elapsed time=120::
+
+# BEGIN TAXI_SAMPLE_RUN
+$ python3 taxi_sim.py -s 3 -e 120
+taxi: 0  Event(time=0, proc=0, action='leave garage')
+taxi: 0  Event(time=2, proc=0, action='pick up passenger')
+taxi: 1     Event(time=5, proc=1, action='leave garage')
+taxi: 1     Event(time=8, proc=1, action='pick up passenger')
+taxi: 2        Event(time=10, proc=2, action='leave garage')
+taxi: 2        Event(time=15, proc=2, action='pick up passenger')
+taxi: 2        Event(time=17, proc=2, action='drop off passenger')
+taxi: 0  Event(time=18, proc=0, action='drop off passenger')
+taxi: 2        Event(time=18, proc=2, action='pick up passenger')
+taxi: 2        Event(time=25, proc=2, action='drop off passenger')
+taxi: 1     Event(time=27, proc=1, action='drop off passenger')
+taxi: 2        Event(time=27, proc=2, action='pick up passenger')
+taxi: 0  Event(time=28, proc=0, action='pick up passenger')
+taxi: 2        Event(time=40, proc=2, action='drop off passenger')
+taxi: 2        Event(time=44, proc=2, action='pick up passenger')
+taxi: 1     Event(time=55, proc=1, action='pick up passenger')
+taxi: 1     Event(time=59, proc=1, action='drop off passenger')
+taxi: 0  Event(time=65, proc=0, action='drop off passenger')
+taxi: 1     Event(time=65, proc=1, action='pick up passenger')
+taxi: 2        Event(time=65, proc=2, action='drop off passenger')
+taxi: 2        Event(time=72, proc=2, action='pick up passenger')
+taxi: 0  Event(time=76, proc=0, action='going home')
+taxi: 1     Event(time=80, proc=1, action='drop off passenger')
+taxi: 1     Event(time=88, proc=1, action='pick up passenger')
+taxi: 2        Event(time=95, proc=2, action='drop off passenger')
+taxi: 2        Event(time=97, proc=2, action='pick up passenger')
+taxi: 2        Event(time=98, proc=2, action='drop off passenger')
+taxi: 1     Event(time=106, proc=1, action='drop off passenger')
+taxi: 2        Event(time=109, proc=2, action='going home')
+taxi: 1     Event(time=110, proc=1, action='going home')
+*** end of events ***
+# END TAXI_SAMPLE_RUN
+
+"""

16-coroutine/taxi_sim_delay.py

@@ -0,0 +1,215 @@
+
+"""
+Taxi simulator with delay on output
+===================================
+
+This is a variation of ``taxi_sim.py`` which adds a ``-d`` comand-line
+option. When given, that option adds a delay in the main loop, pausing
+the simulation for .5s for each "minute" of simulation time.
+
+
+Driving a taxi from the console::
+
+    >>> from taxi_sim import taxi_process
+    >>> taxi = taxi_process(ident=13, trips=2, start_time=0)
+    >>> next(taxi)
+    Event(time=0, proc=13, action='leave garage')
+    >>> taxi.send(_.time + 7)
+    Event(time=7, proc=13, action='pick up passenger')
+    >>> taxi.send(_.time + 23)
+    Event(time=30, proc=13, action='drop off passenger')
+    >>> taxi.send(_.time + 5)
+    Event(time=35, proc=13, action='pick up passenger')
+    >>> taxi.send(_.time + 48)
+    Event(time=83, proc=13, action='drop off passenger')
+    >>> taxi.send(_.time + 1)
+    Event(time=84, proc=13, action='going home')
+    >>> taxi.send(_.time + 10)
+    Traceback (most recent call last):
+      File "<stdin>", line 1, in <module>
+    StopIteration
+
+Sample run with two cars, random seed 10. This is a valid doctest::
+
+    >>> main(num_taxis=2, seed=10)
+    taxi: 0  Event(time=0, proc=0, action='leave garage')
+    taxi: 0  Event(time=5, proc=0, action='pick up passenger')
+    taxi: 1     Event(time=5, proc=1, action='leave garage')
+    taxi: 1     Event(time=10, proc=1, action='pick up passenger')
+    taxi: 1     Event(time=15, proc=1, action='drop off passenger')
+    taxi: 0  Event(time=17, proc=0, action='drop off passenger')
+    taxi: 1     Event(time=24, proc=1, action='pick up passenger')
+    taxi: 0  Event(time=26, proc=0, action='pick up passenger')
+    taxi: 0  Event(time=30, proc=0, action='drop off passenger')
+    taxi: 0  Event(time=34, proc=0, action='going home')
+    taxi: 1     Event(time=46, proc=1, action='drop off passenger')
+    taxi: 1     Event(time=48, proc=1, action='pick up passenger')
+    taxi: 1     Event(time=110, proc=1, action='drop off passenger')
+    taxi: 1     Event(time=139, proc=1, action='pick up passenger')
+    taxi: 1     Event(time=140, proc=1, action='drop off passenger')
+    taxi: 1     Event(time=150, proc=1, action='going home')
+    *** end of events ***
+
+See longer sample run at the end of this module.
+
+"""
+
+import random
+import collections
+import queue
+import argparse
+import time
+
+DEFAULT_NUMBER_OF_TAXIS = 3
+DEFAULT_END_TIME = 180
+SEARCH_DURATION = 5
+TRIP_DURATION = 20
+DEPARTURE_INTERVAL = 5
+
+Event = collections.namedtuple('Event', 'time proc action')
+
+
+# BEGIN TAXI_PROCESS
+def taxi_process(ident, trips, start_time=0):  # <1>
+    """Yield to simulator issuing event at each state change"""
+    time = yield Event(start_time, ident, 'leave garage')  # <2>
+    for i in range(trips):  # <3>
+        time = yield Event(time, ident, 'pick up passenger')  # <4>
+        time = yield Event(time, ident, 'drop off passenger')  # <5>
+
+    yield Event(time, ident, 'going home')  # <6>
+    # end of taxi process # <7>
+# END TAXI_PROCESS
+
+
+# BEGIN TAXI_SIMULATOR
+class Simulator:
+
+    def __init__(self, procs_map):
+        self.events = queue.PriorityQueue()
+        self.procs = dict(procs_map)
+
+    def run(self, end_time, delay=False):  # <1>
+        """Schedule and display events until time is up"""
+        # schedule the first event for each cab
+        for _, proc in sorted(self.procs.items()):  # <2>
+            first_event = next(proc)  # <3>
+            self.events.put(first_event)  # <4>
+
+        # main loop of the simulation
+        sim_time = 0  # <5>
+        while sim_time < end_time:  # <6>
+            if self.events.empty():  # <7>
+                print('*** end of events ***')
+                break
+
+            # get and display current event
+            current_event = self.events.get()  # <8>
+            if delay:
+                time.sleep((current_event.time - sim_time) / 2)
+            # update the simulation time
+            sim_time, proc_id, previous_action = current_event
+            print('taxi:', proc_id, proc_id * '   ', current_event)
+            active_proc = self.procs[proc_id]
+            # schedule next action for current proc
+            next_time = sim_time + compute_duration(previous_action)
+            try:
+                next_event = active_proc.send(next_time)  # <12>
+            except StopIteration:
+                del self.procs[proc_id]  # <13>
+            else:
+                self.events.put(next_event)  # <14>
+        else:  # <15>
+            msg = '*** end of simulation time: {} events pending ***'
+            print(msg.format(self.events.qsize()))
+# END TAXI_SIMULATOR
+
+
+def compute_duration(previous_action):
+    """Compute action duration using exponential distribution"""
+    if previous_action in ['leave garage', 'drop off passenger']:
+        # new state is prowling
+        interval = SEARCH_DURATION
+    elif previous_action == 'pick up passenger':
+        # new state is trip
+        interval = TRIP_DURATION
+    elif previous_action == 'going home':
+        interval = 1
+    else:
+        raise ValueError('Unknown previous_action: %s' % previous_action)
+    return int(random.expovariate(1/interval)) + 1
+
+
+def main(end_time=DEFAULT_END_TIME, num_taxis=DEFAULT_NUMBER_OF_TAXIS,
+         seed=None, delay=False):
+    """Initialize random generator, build procs and run simulation"""
+    if seed is not None:
+        random.seed(seed)  # get reproducible results
+
+    taxis = {i: taxi_process(i, (i+1)*2, i*DEPARTURE_INTERVAL)
+             for i in range(num_taxis)}
+    sim = Simulator(taxis)
+    sim.run(end_time, delay)
+
+
+if __name__ == '__main__':
+
+    parser = argparse.ArgumentParser(
+                        description='Taxi fleet simulator.')
+    parser.add_argument('-e', '--end-time', type=int,
+                        default=DEFAULT_END_TIME,
+                        help='simulation end time; default = %s'
+                        % DEFAULT_END_TIME)
+    parser.add_argument('-t', '--taxis', type=int,
+                        default=DEFAULT_NUMBER_OF_TAXIS,
+                        help='number of taxis running; default = %s'
+                        % DEFAULT_NUMBER_OF_TAXIS)
+    parser.add_argument('-s', '--seed', type=int, default=None,
+                        help='random generator seed (for testing)')
+    parser.add_argument('-d', '--delay', action='store_true',
+                        help='introduce delay proportional to simulation time')
+
+    args = parser.parse_args()
+    main(args.end_time, args.taxis, args.seed, args.delay)
+
+
+"""
+
+Sample run from the command line, seed=3, maximum elapsed time=120::
+
+# BEGIN TAXI_SAMPLE_RUN
+$ python3 taxi_sim.py -s 3 -e 120
+taxi: 0  Event(time=0, proc=0, action='leave garage')
+taxi: 0  Event(time=2, proc=0, action='pick up passenger')
+taxi: 1     Event(time=5, proc=1, action='leave garage')
+taxi: 1     Event(time=8, proc=1, action='pick up passenger')
+taxi: 2        Event(time=10, proc=2, action='leave garage')
+taxi: 2        Event(time=15, proc=2, action='pick up passenger')
+taxi: 2        Event(time=17, proc=2, action='drop off passenger')
+taxi: 0  Event(time=18, proc=0, action='drop off passenger')
+taxi: 2        Event(time=18, proc=2, action='pick up passenger')
+taxi: 2        Event(time=25, proc=2, action='drop off passenger')
+taxi: 1     Event(time=27, proc=1, action='drop off passenger')
+taxi: 2        Event(time=27, proc=2, action='pick up passenger')
+taxi: 0  Event(time=28, proc=0, action='pick up passenger')
+taxi: 2        Event(time=40, proc=2, action='drop off passenger')
+taxi: 2        Event(time=44, proc=2, action='pick up passenger')
+taxi: 1     Event(time=55, proc=1, action='pick up passenger')
+taxi: 1     Event(time=59, proc=1, action='drop off passenger')
+taxi: 0  Event(time=65, proc=0, action='drop off passenger')
+taxi: 1     Event(time=65, proc=1, action='pick up passenger')
+taxi: 2        Event(time=65, proc=2, action='drop off passenger')
+taxi: 2        Event(time=72, proc=2, action='pick up passenger')
+taxi: 0  Event(time=76, proc=0, action='going home')
+taxi: 1     Event(time=80, proc=1, action='drop off passenger')
+taxi: 1     Event(time=88, proc=1, action='pick up passenger')
+taxi: 2        Event(time=95, proc=2, action='drop off passenger')
+taxi: 2        Event(time=97, proc=2, action='pick up passenger')
+taxi: 2        Event(time=98, proc=2, action='drop off passenger')
+taxi: 1     Event(time=106, proc=1, action='drop off passenger')
+taxi: 2        Event(time=109, proc=2, action='going home')
+taxi: 1     Event(time=110, proc=1, action='going home')
+*** end of events ***
+# END TAXI_SAMPLE_RUN
+
+"""

16-coroutine/yield_from_expansion_simplified.py

@@ -0,0 +1,32 @@
+# Code below is a very simplified expansion of the statement:
+#
+# RESULT = yield from EXPR
+#
+# This code assumes that the subgenerator will run to completion,
+# without the client ever calling ``.throw()`` or ``.close()``.
+# Also, this code makes no distinction between the client
+# calling ``next(subgen)`` or ``subgen.send(...)``
+#
+# The full expansion is in:
+# PEP 380 -- Syntax for Delegating to a Subgenerator
+#
+# https://www.python.org/dev/peps/pep-0380/#formal-semantics
+
+
+# BEGIN YIELD_FROM_EXPANSION_SIMPLIFIED
+_i = iter(EXPR)  # <1>
+try:
+    _y = next(_i)  # <2>
+except StopIteration as _e:
+    _r = _e.value  # <3>
+else:
+    while 1:  # <4>
+        _s = yield _y  # <5>
+        try:
+            _y = _i.send(_s)  # <6>
+        except StopIteration as _e:  # <7>
+            _r = _e.value
+            break
+
+RESULT = _r  # <8>
+# END YIELD_FROM_EXPANSION_SIMPLIFIED

17-futures/countries/flags2_asyncio.py

@@ -92,25 +92,23 @@ def downloader_coro(cc_list, base_url, verbose, concur_req):  # <1>
                 error_msg = exc.__cause__.args[0]  # <10>
             except IndexError:
                 error_msg = exc.__cause__.__class__.__name__  # <11>
+            if verbose and error_msg:
+                msg = '*** Error for {}: {}'
+                print(msg.format(country_code, error_msg))
+            status = HTTPStatus.error
         else:
-            error_msg = ''
             status = res.status
 
-        if error_msg:  # <12>
-            status = HTTPStatus.error
-        counter[status] += 1
-        if verbose and error_msg:
-            msg = '*** Error for {}: {}'
-            print(msg.format(country_code, error_msg))
+        counter[status] += 1  # <12>
 
-    return counter
+    return counter  # <13>
 
 
 def download_many(cc_list, base_url, verbose, concur_req):
     loop = asyncio.get_event_loop()
     coro = downloader_coro(cc_list, base_url, verbose, concur_req)
-    counts = loop.run_until_complete(coro)  # <13>
-    loop.close()  # <14>
+    counts = loop.run_until_complete(coro)  # <14>
+    loop.close()  # <15>
 
     return counts
 

17-futures/countries/flags2_threadpool.py

@@ -38,10 +38,10 @@ def download_many(cc_list, base_url, verbose, concur_req):
             future = executor.submit(download_one,
                             cc, base_url, verbose)  # <9>
             to_do_map[future] = cc  # <10>
-        to_do_iter = futures.as_completed(to_do_map)  # <11>
+        done_iter = futures.as_completed(to_do_map)  # <11>
         if not verbose:
-            to_do_iter = tqdm.tqdm(to_do_iter, total=len(cc_list))  # <12>
-        for future in to_do_iter:  # <13>
+            done_iter = tqdm.tqdm(done_iter, total=len(cc_list))  # <12>
+        for future in done_iter:  # <13>
             try:
                 res = future.result()  # <14>
             except requests.exceptions.HTTPError as exc:  # <15>

17-futures/countries/flags3_asyncio.py

@@ -105,16 +105,14 @@ def downloader_coro(cc_list, base_url, verbose, concur_req):
                 error_msg = exc.__cause__.args[0]
             except IndexError:
                 error_msg = exc.__cause__.__class__.__name__
+            if verbose and error_msg:
+                msg = '*** Error for {}: {}'
+                print(msg.format(country_code, error_msg))
+            status = HTTPStatus.error
         else:
-            error_msg = ''
             status = res.status
 
-        if error_msg:
-            status = HTTPStatus.error
         counter[status] += 1
-        if verbose and error_msg:
-            msg = '*** Error for {}: {}'
-            print(msg.format(country_code, error_msg))
 
     return counter
 

18-asyncio/spinner_asyncio.py

@@ -10,8 +10,8 @@ import itertools
 import sys
 
 
-@asyncio.coroutine
-def spin(msg):  # <1>
+@asyncio.coroutine  # <1>
+def spin(msg):  # <2>
     write, flush = sys.stdout.write, sys.stdout.flush
     for char in itertools.cycle('|/-\\'):
         status = char + ' ' + msg
@@ -19,31 +19,31 @@ def spin(msg):  # <1>
         flush()
         write('\x08' * len(status))
         try:
-            yield from asyncio.sleep(.1)  # <2>
-        except asyncio.CancelledError:  # <3>
+            yield from asyncio.sleep(.1)  # <3>
+        except asyncio.CancelledError:  # <4>
             break
     write(' ' * len(status) + '\x08' * len(status))
 
 
 @asyncio.coroutine
-def slow_computation():  # <4>
-    # fake computation waiting a long time for I/O
-    yield from asyncio.sleep(3)  # <5>
+def slow_function():  # <5>
+    # pretend waiting a long time for I/O
+    yield from asyncio.sleep(3)  # <6>
     return 42
 
 
 @asyncio.coroutine
-def supervisor():  # <6>
-    spinner = asyncio.async(spin('thinking!'))  # <7>
-    print('spinner object:', spinner)  # <8>
-    result = yield from slow_computation()  # <9>
-    spinner.cancel()  # <10>
+def supervisor():  # <7>
+    spinner = asyncio.async(spin('thinking!'))  # <8>
+    print('spinner object:', spinner)  # <9>
+    result = yield from slow_function()  # <10>
+    spinner.cancel()  # <11>
     return result
 
 
 def main():
-    loop = asyncio.get_event_loop()  # <11>
-    result = loop.run_until_complete(supervisor())  # <12>
+    loop = asyncio.get_event_loop()  # <12>
+    result = loop.run_until_complete(supervisor())  # <13>
     loop.close()
     print('Answer:', result)
 

18-asyncio/spinner_thread.py

@@ -28,19 +28,19 @@ def spin(msg, signal):  # <2>
     write(' ' * len(status) + '\x08' * len(status))  # <6>
 
 
-def slow_computation():  # <7>
-    # fake computation waiting a long time for I/O
+def slow_function():  # <7>
+    # pretend waiting a long time for I/O
     time.sleep(3)  # <8>
     return 42
 
 
 def supervisor():  # <9>
     signal = Signal()
-    spinner = threading.Thread(None, spin,
+    spinner = threading.Thread(target=spin,
                                args=('thinking!', signal))
     print('spinner object:', spinner)  # <10>
     spinner.start()  # <11>
-    result = slow_computation()  # <12>
+    result = slow_function()  # <12>
     signal.go = False  # <13>
     spinner.join()  # <14>
     return result

19-dyn-attr-prop/oscon/explore0.py

@@ -1,7 +1,7 @@
 """
-explore1.py: Script to explore the OSCON schedule feed
+explore0.py: Script to explore the OSCON schedule feed
 
-# BEGIN EXPLORE1_DEMO
+# BEGIN EXPLORE0_DEMO
     >>> from osconfeed import load
     >>> raw_feed = load()
     >>> feed = FrozenJSON(raw_feed)  # <1>
@@ -18,7 +18,9 @@ explore1.py: Script to explore the OSCON schedule feed
      53 venues
     >>> feed.Schedule.speakers[-1].name  # <5>
     'Carina C. Zona'
-    >>> talk = feed.Schedule.events[40]  # <6>
+    >>> talk = feed.Schedule.events[40]
+    >>> type(talk)  # <6>
+    <class 'explore0.FrozenJSON'>
     >>> talk.name
     'There *Will* Be Bugs'
     >>> talk.speakers  # <7>
@@ -28,10 +30,11 @@ explore1.py: Script to explore the OSCON schedule feed
       ...
     KeyError: 'flavor'
 
-# END EXPLORE1_DEMO
+# END EXPLORE0_DEMO
+
 """
 
-# BEGIN EXPLORE1
+# BEGIN EXPLORE0
 from collections import abc
 
 
@@ -57,4 +60,4 @@ class FrozenJSON:
             return [cls.build(item) for item in obj]
         else:  # <8>
             return obj
-# END EXPLORE1
+# END EXPLORE0

19-dyn-attr-prop/oscon/explore1.py

@@ -0,0 +1,78 @@
+"""
+explore1.py: Script to explore the OSCON schedule feed
+
+    >>> from osconfeed import load
+    >>> raw_feed = load()
+    >>> feed = FrozenJSON(raw_feed)
+    >>> len(feed.Schedule.speakers)
+    357
+    >>> sorted(feed.Schedule.keys())
+    ['conferences', 'events', 'speakers', 'venues']
+    >>> for key, value in sorted(feed.Schedule.items()):
+    ...     print('{:3} {}'.format(len(value), key))
+    ...
+      1 conferences
+    484 events
+    357 speakers
+     53 venues
+    >>> feed.Schedule.speakers[-1].name
+    'Carina C. Zona'
+    >>> talk = feed.Schedule.events[40]
+    >>> type(talk)
+    <class 'explore1.FrozenJSON'>
+    >>> talk.name
+    'There *Will* Be Bugs'
+    >>> talk.speakers
+    [3471, 5199]
+    >>> talk.flavor
+    Traceback (most recent call last):
+      ...
+    KeyError: 'flavor'
+
+Handle keywords by appending a `_`.
+
+# BEGIN EXPLORE1_DEMO
+
+    >>> grad = FrozenJSON({'name': 'Jim Bo', 'class': 1982})
+    >>> grad.name
+    'Jim Bo'
+    >>> grad.class_
+    1991
+
+# END EXPLORE1_DEMO
+
+"""
+
+from collections import abc
+import keyword
+
+
+class FrozenJSON:
+    """A read-only façade for navigating a JSON-like object
+       using attribute notation
+    """
+
+# BEGIN EXPLORE1
+    def __init__(self, mapping):
+        self.__data = {}
+        for key, value in mapping.items():
+            if keyword.iskeyword(key):  # <1>
+                key += '_'
+            self.__data[key] = value
+# END EXPLORE1
+
+    def __getattr__(self, name):
+        if hasattr(self.__data, name):
+            return getattr(self.__data, name)
+        else:
+            return FrozenJSON.build(self.__data[name])
+
+    @classmethod
+    def build(cls, obj):
+        if isinstance(obj, abc.Mapping):
+            return cls(obj)
+        elif isinstance(obj, abc.MutableSequence):
+            return [cls.build(item) for item in obj]
+        else:  # <8>
+            return obj
+

19-dyn-attr-prop/oscon/explore2.py

@@ -40,7 +40,11 @@ class FrozenJSON:
             return arg
 
     def __init__(self, mapping):
-        self.__data = dict(mapping)
+        self.__data = {}
+        for key, value in mapping.items():
+            if iskeyword(key):
+                key += '_'
+            self.__data[key] = value
 
     def __getattr__(self, name):
         if hasattr(self.__data, name):

control/referencias.txt

@@ -1,12 +0,0 @@
-What's New in Python 2.5 - PEP 342: New Generator Features
-http://docs.python.org/release/2.5/whatsnew/pep-342.html
-
-PEP 342 -- Coroutines via Enhanced Generators
-http://www.python.org/dev/peps/pep-0342/
-
-PEP 380 -- Syntax for Delegating to a Subgenerator
-http://www.python.org/dev/peps/pep-0380/
-
-Coroutines For the Working Python Developer
-http://sdiehl.github.io/coroutine-tutorial/
-

control/taxi_sim2.py

@@ -1,270 +0,0 @@
-
-"""
-Taxi simulator
-
-Sample run with two cars, random seed 10. This is a valid doctest.
-
-    >>> main(num_taxis=2, seed=10)
-    taxi: 0  Event(time=0, proc=0, action='leave garage')
-    taxi: 0  Event(time=4, proc=0, action='pick up passenger')
-    taxi: 1     Event(time=5, proc=1, action='leave garage')
-    taxi: 1     Event(time=9, proc=1, action='pick up passenger')
-    taxi: 0  Event(time=10, proc=0, action='drop off passenger')
-    taxi: 1     Event(time=12, proc=1, action='drop off passenger')
-    taxi: 0  Event(time=17, proc=0, action='pick up passenger')
-    taxi: 1     Event(time=19, proc=1, action='pick up passenger')
-    taxi: 1     Event(time=21, proc=1, action='drop off passenger')
-    taxi: 1     Event(time=24, proc=1, action='pick up passenger')
-    taxi: 0  Event(time=28, proc=0, action='drop off passenger')
-    taxi: 1     Event(time=28, proc=1, action='drop off passenger')
-    taxi: 0  Event(time=29, proc=0, action='going home')
-    taxi: 1     Event(time=30, proc=1, action='pick up passenger')
-    taxi: 1     Event(time=61, proc=1, action='drop off passenger')
-    taxi: 1     Event(time=62, proc=1, action='going home')
-    *** end of events ***
-
-See explanation and longer sample run at the end of this module.
-
-"""
-
-import random
-import collections
-import queue
-import argparse
-import time
-
-DEFAULT_NUMBER_OF_TAXIS = 3
-DEFAULT_END_TIME = 180
-SEARCH_DURATION = 5
-TRIP_DURATION = 20
-DEPARTURE_INTERVAL = 5
-
-Event = collections.namedtuple('Event', 'time proc action')
-
-
-# BEGIN TAXI_PROCESS
-def taxi_process(ident, trips, start_time=0):  # <1>
-    """Yield to simulator issuing event at each state change"""
-    time = yield Event(start_time, ident, 'leave garage')  # <2>
-    for i in range(trips):  # <3>
-        time = yield Event(time, ident, 'pick up passenger')  # <4>
-        time = yield Event(time, ident, 'drop off passenger')  # <5>
-
-    yield Event(time, ident, 'going home')  # <6>
-    # end of taxi process # <7>
-# END TAXI_PROCESS
-
-
-# BEGIN TAXI_SIMULATOR
-class Simulator:
-
-    def __init__(self, procs_map):
-        self.events = queue.PriorityQueue()
-        self.procs = dict(procs_map)
-
-    def run(self, end_time, delay=False):  # <1>
-        """Schedule and display events until time is up"""
-        # schedule the first event for each cab
-        for _, proc in sorted(self.procs.items()):  # <2>
-            first_event = next(proc)  # <3>
-            self.events.put(first_event)  # <4>
-
-        # main loop of the simulation
-        sim_time = 0  # <5>
-        while sim_time < end_time:  # <6>
-            if self.events.empty():  # <7>
-                print('*** end of events ***')
-                break
-
-            # get and display current event
-            current_event = self.events.get()  # <8>
-            if delay:
-                time.sleep((current_event.time - sim_time) / 2)
-            # update the simulation time
-            sim_time, proc_id, previous_action = current_event
-            print('taxi:', proc_id, proc_id * '   ', current_event)
-            active_proc = self.procs[proc_id]
-            # schedule next action for current proc
-            next_time = sim_time + compute_duration(previous_action)
-            try:
-                next_event = active_proc.send(next_time)  # <12>
-            except StopIteration:
-                del self.procs[proc_id]  # <13>
-            else:
-                self.events.put(next_event)  # <14>
-        else:  # <15>
-            msg = '*** end of simulation time: {} events pending ***'
-            print(msg.format(self.events.qsize()))
-# END TAXI_SIMULATOR
-
-
-def compute_duration(previous_action):
-    """Compute action duration using exponential distribution"""
-    if previous_action in ['leave garage', 'drop off passenger']:
-        # state is prowling
-        interval = SEARCH_DURATION
-    elif previous_action == 'pick up passenger':
-        # state is trip
-        interval = TRIP_DURATION
-    elif previous_action == 'going home':
-        interval = 1
-    else:
-        assert False
-    return int(random.expovariate(1/interval)) + 1
-
-
-def main(end_time=DEFAULT_END_TIME, num_taxis=DEFAULT_NUMBER_OF_TAXIS,
-         seed=None, delay=False):
-    """Initialize random generator, build procs and run simulation"""
-    if seed is not None:
-        random.seed(seed)  # get reproducible results
-
-    taxis = {i: taxi_process(i, (i+1)*2, i*DEPARTURE_INTERVAL)
-             for i in range(num_taxis)}
-    sim = Simulator(taxis)
-    sim.run(end_time, delay)
-
-
-if __name__ == '__main__':
-
-    parser = argparse.ArgumentParser(
-                        description='Taxi fleet simulator.')
-    parser.add_argument('-e', '--end-time', type=int,
-                        default=DEFAULT_END_TIME,
-                        help='simulation end time; default = %s'
-                        % DEFAULT_END_TIME)
-    parser.add_argument('-t', '--taxis', type=int,
-                        default=DEFAULT_NUMBER_OF_TAXIS,
-                        help='number of taxis running; default = %s'
-                        % DEFAULT_NUMBER_OF_TAXIS)
-    parser.add_argument('-s', '--seed', type=int, default=None,
-                        help='random generator seed (for testing)')
-    parser.add_argument('-d', '--delay', action='store_true',
-                        help='introduce delay proportional to simulation time')
-
-    args = parser.parse_args()
-    main(args.end_time, args.taxis, args.seed, args.delay)
-
-
-"""
-Notes for the ``taxi_process`` coroutine::
-
-<1> `taxi_process` will be called once per taxi, creating a generator
-    object to represent its operations. `ident` is the number of the taxi
-    (eg. 0, 1, 2 in the sample run); `trips` is the number of trips this
-    taxi will make before going home; `start_time` is when the taxi
-    leaves the garage.
-
-<2> The first `Event` yielded is `'leave garage'`. This suspends the
-    coroutine, and lets the simulation main loop proceed to the next
-    scheduled event. When it's time to reactivate this process, the main
-    loop will `send` the current simulation time, which is assigned to
-    `time`.
-
-<3> This block will be repeated once for each trip.
-
-<4> The ending time of the search for a passenger is computed.
-
-<5> An `Event` signaling passenger pick up is yielded. The coroutine
-    pauses here. When the time comes to reactivate this coroutine,
-    the main loop will again `send` the current time.
-
-<6> The ending time of the trip is computed, taking into account the
-    current `time`.
-
-<7> An `Event` signaling passenger drop off is yielded. Coroutine
-    suspended again, waiting for the main loop to send the time of when
-    it's time to continue.
-
-<8> The `for` loop ends after the given number of trips, and a final
-    `'going home'` event is yielded, to happen 1 minute after the current
-    time. The coroutine will suspend for the last time. When reactivated,
-    it will be sent the time from the simulation main loop, but here I
-    don't assign it to any variable because it will not be useful.
-
-<9> When the coroutine falls off the end, the coroutine object raises
-    `StopIteration`.
-
-
-Notes for the ``Simulator.run`` method::
-
-<1> The simulation `end_time` is the only required argument for `run`.
-
-<2> Use `sorted` to retrieve the `self.procs` items ordered by the
-    integer key; we don't care about the key, so assign it to `_`.
-
-<3> `next(proc)` primes each coroutine by advancing it to the first
-    yield, so it's ready to be sent data. An `Event` is yielded.
-
-<4> Add each event to the `self.events` `PriorityQueue`. The first
-    event for each taxi is `'leave garage'`, as seen in the sample run
-    (ex_taxi_process>>).
-
-<5> Main loop of the simulation: run until the current `time` equals
-    or exceeds the `end_time`.
-
-<6> The main loop may also exit if there are no pending events in the
-    queue.
-
-<7> Get `Event` with the smallest `time` in the queue; this is the
-    `current_event`.
-
-<8> Display the `Event`, identifying the taxi and adding indentation
-    according to the taxi id.
-
-<9> Update the simulation time with the time of the `current_event`.
-
-<10> Retrieve the coroutine for this taxi from the `self.procs`
-     dictionary.
-
-<11> Send the `time` to the coroutine. The coroutine will yield the
-     `next_event` or raise `StopIteration` it's finished.
-
-<12> If `StopIteration` was raised, delete the coroutine from the
-     `self.procs` dictionary.
-
-<13> Otherwise, put the `next_event` in the queue.
-
-<14> If the loop exits because the simulation time passed, display the
-     number of events pending (which may be zero by coincidence,
-     sometimes).
-
-
-Sample run from the command line, seed=24, total elapsed time=160::
-
-# BEGIN TAXI_SAMPLE_RUN
-$ python3 taxi_sim.py -s 24 -e 160
-taxi: 0  Event(time=0, proc=0, action='leave garage')
-taxi: 0  Event(time=5, proc=0, action='pick up passenger')
-taxi: 1     Event(time=5, proc=1, action='leave garage')
-taxi: 1     Event(time=6, proc=1, action='pick up passenger')
-taxi: 2        Event(time=10, proc=2, action='leave garage')
-taxi: 2        Event(time=11, proc=2, action='pick up passenger')
-taxi: 2        Event(time=23, proc=2, action='drop off passenger')
-taxi: 0  Event(time=24, proc=0, action='drop off passenger')
-taxi: 2        Event(time=24, proc=2, action='pick up passenger')
-taxi: 2        Event(time=26, proc=2, action='drop off passenger')
-taxi: 0  Event(time=30, proc=0, action='pick up passenger')
-taxi: 2        Event(time=31, proc=2, action='pick up passenger')
-taxi: 0  Event(time=43, proc=0, action='drop off passenger')
-taxi: 0  Event(time=44, proc=0, action='going home')
-taxi: 2        Event(time=46, proc=2, action='drop off passenger')
-taxi: 2        Event(time=49, proc=2, action='pick up passenger')
-taxi: 1     Event(time=70, proc=1, action='drop off passenger')
-taxi: 2        Event(time=70, proc=2, action='drop off passenger')
-taxi: 2        Event(time=71, proc=2, action='pick up passenger')
-taxi: 2        Event(time=79, proc=2, action='drop off passenger')
-taxi: 1     Event(time=88, proc=1, action='pick up passenger')
-taxi: 2        Event(time=92, proc=2, action='pick up passenger')
-taxi: 2        Event(time=98, proc=2, action='drop off passenger')
-taxi: 2        Event(time=99, proc=2, action='going home')
-taxi: 1     Event(time=102, proc=1, action='drop off passenger')
-taxi: 1     Event(time=104, proc=1, action='pick up passenger')
-taxi: 1     Event(time=135, proc=1, action='drop off passenger')
-taxi: 1     Event(time=136, proc=1, action='pick up passenger')
-taxi: 1     Event(time=151, proc=1, action='drop off passenger')
-taxi: 1     Event(time=152, proc=1, action='going home')
-*** end of events ***
-# END TAXI_SAMPLE_RUN
-
-"""