QUERY · ISSUE

Unix: CPython incompatibility assigning negative values to bytearrays.

openby peterhinchopened 2017-07-09updated 2025-04-04

py-core

This is arguably minor, but I thought it worth flagging up. It also applies to bytes objects.

MicroPython v1.8.7-893-g46b849a on 2017-06-22; linux version
Use Ctrl-D to exit, Ctrl-E for paste mode
>>> a = bytearray([0, 1, -1])
>>> a[2]
255
>>>

Under CPython 3.4.3:

>>> a = bytearray([0, 1, -1])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: byte must be in range(0, 256)

CANDIDATE · ISSUE

bytearray slice assignment from generator produces error

closedby peterhinchopened 2015-08-13updated 2022-06-25

Is this an intentional "micro" difference from Cpython or an oversight? This works in Cpython but produces a "Not implemented" error in MicroPython (on Pyboard).

b = bytearray(20)
b[2:7] = (1 for x in range(5))

While the following workround is trivial I thought it worth flagging up:

b[2:7] = bytes(1 for x in range(5))

Unix: CPython incompatibility assigning negative values to bytearrays.

bytearray slice assignment from generator produces error

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