# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
This package defines units that can also be used as functions of other units.
If called, their arguments are used to initialize the corresponding function
unit (e.g., ``u.mag(u.ct/u.s)``).  Note that the prefixed versions cannot be
called, as it would be unclear what, e.g., ``u.mmag(u.ct/u.s)`` would mean.
"""
from astropy.units.core import _add_prefixes
from .mixin import RegularFunctionUnit, IrreducibleFunctionUnit


_ns = globals()

###########################################################################
# Logarithmic units

# These calls are what core.def_unit would do, but we need to use the callable
# unit versions.  The actual function unit classes get added in logarithmic.

dex = IrreducibleFunctionUnit(['dex'], namespace=_ns,
                              doc="Dex: Base 10 logarithmic unit")

dB = RegularFunctionUnit(['dB', 'decibel'], 0.1 * dex, namespace=_ns,
                         doc="Decibel: ten per base 10 logarithmic unit")

mag = RegularFunctionUnit(['mag'], -0.4 * dex, namespace=_ns,
                          doc=("Astronomical magnitude: "
                               "-2.5 per base 10 logarithmic unit"))

_add_prefixes(mag, namespace=_ns, prefixes=True)

###########################################################################
# CLEANUP

del RegularFunctionUnit
del IrreducibleFunctionUnit

###########################################################################
# DOCSTRING

# This generates a docstring for this module that describes all of the
# standard units defined here.
from astropy.units.utils import generate_unit_summary as _generate_unit_summary
if __doc__ is not None:
    __doc__ += _generate_unit_summary(globals())