circuitpython/docs/library/micropython.rst

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:mod:`micropython` -- MicroPython extensions and internals
==========================================================
.. module:: micropython
:synopsis: access and control MicroPython internals
Functions
---------
.. function:: const(expr)
Used to declare that the expression is a constant so that the compiler can
optimise it. The use of this function should be as follows::
from micropython import const
CONST_X = const(123)
CONST_Y = const(2 * CONST_X + 1)
Constants declared this way are still accessible as global variables from
outside the module they are declared in. On the other hand, if a constant
begins with an underscore then it is hidden, it is not available as a global
variable, and does not take up any memory during execution.
This `const` function is recognised directly by the MicroPython parser and is
provided as part of the :mod:`micropython` module mainly so that scripts can be
written which run under both CPython and MicroPython, by following the above
pattern.