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adjust fixed_header init; (-) loop_forever() #46

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Merged
merged 5 commits into from
Aug 6, 2020
Merged

adjust fixed_header init; (-) loop_forever() #46

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285e0da
adjust fixed_header init; (-) loop_forever()
2bndy5 Jul 21, 2020
1cad196
pub_hdr_fixed & pub_hdr_var simplified init
2bndy5 Jul 26, 2020
044d06c
pleasing black
2bndy5 Jul 26, 2020
d938bc0
(-) MQTT_PUB const; fixed pub_hdr_var.append()
2bndy5 Jul 29, 2020
2c790c0
extend() actually works better with a bytes object
2bndy5 Jul 29, 2020
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28 changes: 5 additions & 23 deletions adafruit_minimqtt/adafruit_minimqtt.py
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Original file line number Diff line number Diff line change
Expand Up @@ -303,8 +303,7 @@ def connect(self, clean_session=True):
raise MMQTTException("Invalid broker address defined.", e)

# Fixed Header
fixed_header = bytearray()
fixed_header.append(0x10)
fixed_header = bytearray([0x10])

# NOTE: Variable header is
# MQTT_HDR_CONNECT = bytearray(b"\x04MQTT\x04\x02\0\0")
Expand Down Expand Up @@ -461,13 +460,11 @@ def publish(self, topic, msg, retain=False, qos=0):
0 <= qos <= 1
), "Quality of Service Level 2 is unsupported by this library."

pub_hdr_fixed = bytearray() # fixed header
pub_hdr_fixed.extend(MQTT_PUB)
pub_hdr_fixed[0] |= retain | qos << 1 # [3.3.1.2], [3.3.1.3]
# fixed header. [3.3.1.2], [3.3.1.3]
pub_hdr_fixed = bytearray([MQTT_PUB[0] | retain | qos << 1])

pub_hdr_var = bytearray() # variable header
pub_hdr_var.append(len(topic) >> 8) # Topic length, MSB
pub_hdr_var.append(len(topic) & 0xFF) # Topic length, LSB
# variable header = 2-byte Topic length (big endian)
pub_hdr_var = struct.pack(">H", len(topic))
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Running the example simpletest on Adafruit CircuitPython 5.3.1 on 2020-07-13; Adafruit PyPortal with samd51j20 throws the following error in the REPL:

Subscribed to test/topic with QOS level 0
Publishing to test/topic
Traceback (most recent call last):
  File "code.py", line 116, in <module>
  File "/lib/adafruit_minimqtt/adafruit_minimqtt.py", line 468, in publish
AttributeError: 'bytes' object has no attribute 'extend'

Instead of extend on L468, we may want to append

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@2bndy5 2bndy5 Jul 29, 2020 •
edited
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I feel like this is a borderline rookie mistake. I tried append() instead, but I still got the same error AttributeError: 'bytes' object has no attribute 'append' However pub_hdr_var += topic.encode() does what we want. The real problem comes from the change to using struct.pack() which returns an immutable bytes object, where methods like append() or extend(bytes([0x00])) (notice the need for conversion from int to bytes when using extend()) can only apply to a mutable bytearray object. So, I've wrapped the struct.pack() into a bytearray(struct.pack()) which allows us to keep using the pub_hdr_var.append() calls on L474 & L475.

pub_hdr_var.extend(topic.encode("utf-8")) # Topic name

remaining_length = 2 + len(msg) + len(topic)
Expand Down Expand Up @@ -688,21 +685,6 @@ def reconnect(self, resub_topics=True):
feed = subscribed_topics.pop()
self.subscribe(feed)

def loop_forever(self):
"""Starts a blocking message loop. Use this
method if you want to run a program forever.
Code below a call to this method will NOT execute.

.. note:: This method is depreciated and will be removed in the
next major release. Please see
`examples/minimqtt_pub_sub_blocking.py <examples.html#basic-forever-loop>`_
for an example of creating a blocking loop which can handle wireless
network events.
"""
while True:
if self._sock.connected:
self.loop()

def loop(self):
"""Non-blocking message loop. Use this method to
check incoming subscription messages.
Expand Down