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circuitpython/docs/library/sys.rst

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:mod:`sys` -- system specific functions
=======================================
.. include:: ../templates/unsupported_in_circuitpython.inc
.. module:: sys
:synopsis: system specific functions
|see_cpython_module| :mod:`cpython:sys`.
Functions
---------
.. 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:: print_exception(exc, file=sys.stdout)
Print exception with a traceback to a file-like object *file* (or
`sys.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.
Constants
---------
.. 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
CircuitPython, it has following attributes:
* *name* - string "circuitpython"
* *version* - tuple (major, minor, micro), e.g. (1, 7, 0)
This object is the recommended way to distinguish CircuitPython 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 CircuitPython.
.. data:: maxsize
Maximum value which a native integer type can hold on the current platform,
or maximum value representable by CircuitPython integer type, if it's smaller
than platform max value (that is the case for CircuitPython 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 = sys.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 CircuitPython 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 the chip on a board, e.g. ``"MicroChip SAMD51"``.
It thus can be used to distinguish one board from another.
If you need to check whether your program runs on CircuitPython (vs other
Python implementation), use `sys.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.