:mod:`usys` -- system specific functions
.. module:: usys :synopsis: system specific functions
|see_cpython_module| :mod:`python:sys`.
.. function:: exit(retval=0, /) Terminate current program with a given exit code. Underlyingly, this function raise as `SystemExit` exception. If an argument is given, its value given as an argument to `SystemExit`.
.. function:: atexit(func)
Register *func* to be called upon termination. *func* must be a callable
that takes no arguments, or ``None`` to disable the call. The ``atexit``
function will return the previous value set by this function, which is
initially ``None``.
.. admonition:: Difference to CPython
:class: attention
This function is a MicroPython extension intended to provide similar
functionality to the :mod:`atexit` module in CPython.
.. function:: print_exception(exc, file=usys.stdout, /)
Print exception with a traceback to a file-like object *file* (or
`usys.stdout` by default).
.. admonition:: Difference to CPython
:class: attention
This is simplified version of a function which appears in the
``traceback`` module in CPython. Unlike ``traceback.print_exception()``,
this function takes just exception value instead of exception type,
exception value, and traceback object; *file* argument should be
positional; further arguments are not supported. CPython-compatible
``traceback`` module can be found in `micropython-lib`.
.. data:: argv A mutable list of arguments the current program was started with.
.. data:: byteorder The byte order of the system (``"little"`` or ``"big"``).
.. data:: implementation
Object with information about the current Python implementation. For
MicroPython, it has following attributes:
* *name* - string "micropython"
* *version* - tuple (major, minor, micro), e.g. (1, 7, 0)
This object is the recommended way to distinguish MicroPython from other
Python implementations (note that it still may not exist in the very
minimal ports).
.. admonition:: Difference to CPython
:class: attention
CPython mandates more attributes for this object, but the actual useful
bare minimum is implemented in MicroPython.
.. data:: maxsize
Maximum value which a native integer type can hold on the current platform,
or maximum value representable by MicroPython integer type, if it's smaller
than platform max value (that is the case for MicroPython ports without
long int support).
This attribute is useful for detecting "bitness" of a platform (32-bit vs
64-bit, etc.). It's recommended to not compare this attribute to some
value directly, but instead count number of bits in it::
bits = 0
v = usys.maxsize
while v:
bits += 1
v >>= 1
if bits > 32:
# 64-bit (or more) platform
...
else:
# 32-bit (or less) platform
# Note that on 32-bit platform, value of bits may be less than 32
# (e.g. 31) due to peculiarities described above, so use "> 16",
# "> 32", "> 64" style of comparisons.
.. data:: modules Dictionary of loaded modules. On some ports, it may not include builtin modules.
.. data:: path A mutable list of directories to search for imported modules.
.. data:: platform The platform that MicroPython is running on. For OS/RTOS ports, this is usually an identifier of the OS, e.g. ``"linux"``. For baremetal ports it is an identifier of a board, e.g. ``"pyboard"`` for the original MicroPython reference board. It thus can be used to distinguish one board from another. If you need to check whether your program runs on MicroPython (vs other Python implementation), use `usys.implementation` instead.
.. data:: stderr Standard error `stream`.
.. data:: stdin Standard input `stream`.
.. data:: stdout Standard output `stream`.
.. data:: version Python language version that this implementation conforms to, as a string.
.. data:: version_info
Python language version that this implementation conforms to, as a tuple of ints.
.. admonition:: Difference to CPython
:class: attention
Only the first three version numbers (major, minor, micro) are supported and
they can be referenced only by index, not by name.