From b689b8b6b2313d5557316fe5b1476aae782f58f8 Mon Sep 17 00:00:00 2001
From: Alexandre Detiste <alexandre.detiste@gmail.com>
Date: Wed, 27 Nov 2024 22:15:48 +0100
Subject: [PATCH 1/3] drop Python2 crumbs 1/2

---
 periodictable/activation.py | 2 --
 periodictable/core.py       | 1 -
 periodictable/formulas.py   | 1 -
 3 files changed, 4 deletions(-)

diff --git a/periodictable/activation.py b/periodictable/activation.py
index 9bf130c..bfecddc 100644
--- a/periodictable/activation.py
+++ b/periodictable/activation.py
@@ -222,8 +222,6 @@
 #     58Ni (n,alpha)
 
 
-from __future__ import division, print_function
-
 from math import exp, log, expm1
 import os
 
diff --git a/periodictable/core.py b/periodictable/core.py
index 8294294..09d3d28 100644
--- a/periodictable/core.py
+++ b/periodictable/core.py
@@ -55,7 +55,6 @@
     periodic table with custom values for the attributes.
 
 """
-from __future__ import print_function
 
 __docformat__ = 'restructuredtext en'
 __all__ = ['delayed_load', 'define_elements', 'get_data_path',
diff --git a/periodictable/formulas.py b/periodictable/formulas.py
index 75e07d0..7209dda 100644
--- a/periodictable/formulas.py
+++ b/periodictable/formulas.py
@@ -3,7 +3,6 @@
 """
 Chemical formula parser.
 """
-from __future__ import division, print_function
 
 from copy import copy
 from math import pi, sqrt

From 91af03a41d91679249c2467307b72d9e14234fb3 Mon Sep 17 00:00:00 2001
From: Alexandre Detiste <alexandre.detiste@gmail.com>
Date: Wed, 27 Nov 2024 22:21:40 +0100
Subject: [PATCH 2/3] remove more Python2 syntax

---
 periodictable/activation.py  |  6 +++---
 periodictable/core.py        | 10 +++++-----
 periodictable/cromermann.py  |  2 +-
 periodictable/fasta.py       |  2 +-
 periodictable/formulas.py    |  2 +-
 periodictable/magnetic_ff.py |  2 +-
 periodictable/nsf.py         |  2 +-
 periodictable/xsf.py         |  2 +-
 8 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/periodictable/activation.py b/periodictable/activation.py
index bfecddc..7d698e2 100644
--- a/periodictable/activation.py
+++ b/periodictable/activation.py
@@ -251,7 +251,7 @@ def IAEA1987_isotopic_abundance(iso):
     except AttributeError:
         return 0
 
-class Sample(object):
+class Sample:
     """
     Sample properties.
 
@@ -452,7 +452,7 @@ def sorted_activity(activity_pair):
     return sorted(activity_pair, key=lambda x: (x[0].isotope, x[0].daughter))
 
 
-class ActivationEnvironment(object):
+class ActivationEnvironment:
     """
     Neutron activation environment.
 
@@ -745,7 +745,7 @@ def activity(isotope, mass, env, exposure, rest_times):
 
     return result
 
-class ActivationResult(object):
+class ActivationResult:
     r"""
     *isotope* :
 
diff --git a/periodictable/core.py b/periodictable/core.py
index 09d3d28..84f5675 100644
--- a/periodictable/core.py
+++ b/periodictable/core.py
@@ -151,7 +151,7 @@ def setfn(el, value):
             setattr(Ion, p, prop)
 
 # Define the element names from the element table.
-class PeriodicTable(object):
+class PeriodicTable:
     """
     Defines the periodic table of the elements with isotopes.
     Individidual elements are accessed by name, symbol or atomic number.
@@ -411,7 +411,7 @@ def list(self, *props, **kw):
                 #    print "format", format, "args", L
                 #    raise
 
-class IonSet(object):
+class IonSet:
     def __init__(self, element_or_isotope):
         self.element_or_isotope = element_or_isotope
         self.ionset = {}
@@ -424,7 +424,7 @@ def __getitem__(self, charge):
             self.ionset[charge] = Ion(self.element_or_isotope, charge)
         return self.ionset[charge]
 
-class Ion(object):
+class Ion:
     """
     Periodic table entry for an individual ion.
 
@@ -459,7 +459,7 @@ def __reduce__(self):
                                self.element.number,
                                self.charge)
 
-class Isotope(object):
+class Isotope:
     """
     Periodic table entry for an individual isotope.
 
@@ -487,7 +487,7 @@ def __reduce__(self):
                                self.element.number,
                                self.isotope)
 
-class Element(object):
+class Element:
     """
     Periodic table entry for an element.
 
diff --git a/periodictable/cromermann.py b/periodictable/cromermann.py
index 6b575ae..ea18a8d 100644
--- a/periodictable/cromermann.py
+++ b/periodictable/cromermann.py
@@ -110,7 +110,7 @@ def fxrayatstol(symbol, stol, charge=None):
     return rv
 
 
-class CromerMannFormula(object):
+class CromerMannFormula:
     """
     Cromer-Mann formula for x-ray scattering factors.
     Coefficient storage and evaluation.
diff --git a/periodictable/fasta.py b/periodictable/fasta.py
index 8b4372b..7110d0e 100644
--- a/periodictable/fasta.py
+++ b/periodictable/fasta.py
@@ -98,7 +98,7 @@ def isotope_substitution(formula, source, target, portion=1):
     return formula.replace(source, target, portion=portion)
 
 # TODO: allow Molecule to be used as compound in formulas.formula()
-class Molecule(object):
+class Molecule:
     """
     Specify a biomolecule by name, chemical formula, cell volume and charge.
 
diff --git a/periodictable/formulas.py b/periodictable/formulas.py
index 7209dda..31ad42e 100644
--- a/periodictable/formulas.py
+++ b/periodictable/formulas.py
@@ -305,7 +305,7 @@ def formula(compound=None, density=None, natural_density=None,
     return Formula(structure=structure, name=name, density=density,
                    natural_density=natural_density)
 
-class Formula(object):
+class Formula:
     """
     Simple chemical formula representation.
 
diff --git a/periodictable/magnetic_ff.py b/periodictable/magnetic_ff.py
index c9bbb63..eb4acff 100644
--- a/periodictable/magnetic_ff.py
+++ b/periodictable/magnetic_ff.py
@@ -34,7 +34,7 @@ def formfactor_n(jn, q):
     return s_sq * (A * exp(-a*s_sq) + B * exp(-b*s_sq) + C * exp(-c*s_sq) + D)
 
 
-class MagneticFormFactor(object):
+class MagneticFormFactor:
     """
     Magnetic form factor for the ion.
 
diff --git a/periodictable/nsf.py b/periodictable/nsf.py
index a0d2558..87f404e 100644
--- a/periodictable/nsf.py
+++ b/periodictable/nsf.py
@@ -327,7 +327,7 @@ def _CHECK_scattering_potential(sld):
     return (ENERGY_FACTOR/pi) * asarray(sld)
 
 _4PI_100 = 4*np.pi/100
-class Neutron(object):
+class Neutron:
     r"""
     Neutron scattering factors are attached to each element in the periodic
     table for which values are available.  If no information is available,
diff --git a/periodictable/xsf.py b/periodictable/xsf.py
index eb52b92..eae2591 100644
--- a/periodictable/xsf.py
+++ b/periodictable/xsf.py
@@ -243,7 +243,7 @@ def xray_energy(wavelength):
     """
     return planck_constant/electron_volt*speed_of_light/np.asarray(wavelength)*1e7
 
-class Xray(object):
+class Xray:
     """
     X-ray scattering properties for the elements. Refer help(periodictable.xsf)
     from command prompt for details.

From a7e11f851fcb14d558abb59504774c6529e8047f Mon Sep 17 00:00:00 2001
From: Alexandre Detiste <alexandre.detiste@gmail.com>
Date: Wed, 27 Nov 2024 22:27:07 +0100
Subject: [PATCH 3/3] replace custom @require_keywords decorator with modern
 syntax

---
 periodictable/formulas.py |  8 ++---
 periodictable/nsf.py      | 11 +++---
 periodictable/util.py     | 71 ---------------------------------------
 periodictable/xsf.py      | 16 +++------
 4 files changed, 12 insertions(+), 94 deletions(-)

diff --git a/periodictable/formulas.py b/periodictable/formulas.py
index 31ad42e..5940f2b 100644
--- a/periodictable/formulas.py
+++ b/periodictable/formulas.py
@@ -14,7 +14,7 @@
 
 from .core import default_table, isatom, isisotope, ision, change_table
 from .constants import avogadro_number
-from .util import require_keywords, cell_volume
+from .util import cell_volume
 
 PACKING_FACTORS = dict(cubic=pi/6, bcc=pi*sqrt(3)/8, hcp=pi/sqrt(18),
                        fcc=pi/sqrt(18), diamond=pi*sqrt(3)/16)
@@ -518,8 +518,7 @@ def volume(self, *args, **kw):
             packing_factor = PACKING_FACTORS[packing_factor.lower()]
         return V/packing_factor*1e-24
 
-    @require_keywords
-    def neutron_sld(self, wavelength=None, energy=None):
+    def neutron_sld(self, *, wavelength=None, energy=None):
         """
         Neutron scattering information for the molecule.
 
@@ -543,8 +542,7 @@ def neutron_sld(self, wavelength=None, energy=None):
         return neutron_sld(self.atoms, density=self.density,
                            wavelength=wavelength, energy=energy)
 
-    @require_keywords
-    def xray_sld(self, energy=None, wavelength=None):
+    def xray_sld(self, *, energy=None, wavelength=None):
         """
         X-ray scattering length density for the molecule.
 
diff --git a/periodictable/nsf.py b/periodictable/nsf.py
index 87f404e..63abfe1 100644
--- a/periodictable/nsf.py
+++ b/periodictable/nsf.py
@@ -188,7 +188,7 @@
 from .core import Element, Isotope, default_table
 from .constants import (avogadro_number, planck_constant, electron_volt,
                         neutron_mass, atomic_mass_constant)
-from .util import require_keywords, parse_uncertainty
+from .util import parse_uncertainty
 
 __all__ = ['init', 'Neutron',
            'neutron_energy', 'neutron_wavelength',
@@ -483,8 +483,7 @@ def scattering_by_wavelength(self, wavelength):
         sigma_s = _4PI_100*abs(b_c)**2 # 1 barn = 1 fm^2 1e-2 barn/fm^2
         return b_c, sigma_s
 
-    @require_keywords
-    def sld(self, wavelength=ABSORPTION_WAVELENGTH):
+    def sld(self, *, wavelength=ABSORPTION_WAVELENGTH):
         r"""
         Returns scattering length density for the element at natural
         abundance and density.
@@ -505,8 +504,7 @@ def sld(self, wavelength=ABSORPTION_WAVELENGTH):
             return None, None, None
         return self.scattering(wavelength=wavelength)[0]
 
-    @require_keywords
-    def scattering(self, wavelength=ABSORPTION_WAVELENGTH):
+    def scattering(self, *, wavelength=ABSORPTION_WAVELENGTH):
         r"""
         Returns neutron scattering information for the element at natural
         abundance and density.
@@ -650,8 +648,7 @@ def init(table, reload=False):
 # TODO: split incoherent into spin and isotope incoherence (eq 17-19 of Sears)
 # TODO: require parsed compound rather than including formula() keywords in api
 # Note: docs and function prototype are reproduced in __init__
-@require_keywords
-def neutron_scattering(compound, density=None,
+def neutron_scattering(compound, *, density=None,
                        wavelength=None, energy=None,
                        natural_density=None, table=None):
     r"""
diff --git a/periodictable/util.py b/periodictable/util.py
index 2f9c25e..e729547 100644
--- a/periodictable/util.py
+++ b/periodictable/util.py
@@ -91,74 +91,3 @@ def cell_volume(a=None, b=None, c=None, alpha=None, beta=None, gamma=None):
     cgamma = cos(radians(gamma)) if gamma is not None else calpha
     V = a*b*c*sqrt(1 - calpha**2 - cbeta**2 - cgamma**2 + 2*calpha*cbeta*cgamma)
     return V
-
-def require_keywords(function):
-    r"""
-    Decorator which forces all keyword arguments to the function to be
-    explicitly named.
-
-    For example:
-
-        >>> @require_keywords
-        ... def fn(a, b, c=3): pass
-        >>> fn(1, 2, 3)
-        Traceback (most recent call last):
-        ...
-        TypeError: name=value required for c
-        >>> fn(1, 2, c=6)
-        >>> fn(b=1, a=2, c=6)
-
-    Variable arguments are not currently supported:
-
-        >>> @require_keywords
-        ... def fn(a, b, c=6, *args, **kw): pass
-        Traceback (most recent call last):
-        ...
-        NotImplementedError: only named arguments for now
-
-    .. Note:: The call signature is not preserved.
-
-    We can't preserve the function signature for the call since the only
-    way we can count the number of non-keyword arguments is to
-    use the \*args, \*\*kw call style.  Python 3+ provides the '\*' call
-    signature element which will force all keywords after '\*' to be named.
-    """
-    import functools
-    try:
-        from inspect import signature
-        getargspec = _getargspec_from_signature
-    except ImportError: # CRUFT: py 2.7 support
-        from inspect import getargspec
-
-    args, vararg, varkwd, defaults = getargspec(function)
-    if defaults is None:
-        defaults = []
-    named_args = args[:-len(defaults)]
-    named_kwds = args[-len(defaults):]
-    # Keep it simple for now
-    if vararg or varkwd:
-        raise NotImplementedError("only named arguments for now")
-    @functools.wraps(function)
-    def _require_kwds(*args, **kw):
-        if len(args) > len(named_args):
-            raise TypeError("name=value required for "+", ".join(named_kwds))
-        return function(*args, **kw)
-    return _require_kwds
-
-def _getargspec_from_signature(function):
-    """
-    Reproduce getargspec() interface using newer signature protocol
-    """
-    from inspect import signature
-
-    args, vararg, varkwd, defaults = [], None, None, []
-    sig = signature(function)
-    for p in sig.parameters.values():
-        args.append(p.name)
-        if p.default is not p.empty:
-            defaults.append(p.default)
-        if p.kind is p.VAR_POSITIONAL:
-            vararg = p.name
-        elif p.kind is p.VAR_KEYWORD:
-            varkwd = p.name
-    return args, vararg, varkwd, defaults
diff --git a/periodictable/xsf.py b/periodictable/xsf.py
index eae2591..a1a5950 100644
--- a/periodictable/xsf.py
+++ b/periodictable/xsf.py
@@ -193,7 +193,6 @@
 from .constants import (
     avogadro_number, planck_constant, speed_of_light, electron_volt,
     electron_radius)
-from .util import require_keywords
 
 def xray_wavelength(energy):
     r"""
@@ -271,8 +270,7 @@ def _gettable(self):
         return self._table
     sftable = property(_gettable, doc="X-ray scattering factor table (E,f1,f2)")
 
-    @require_keywords
-    def scattering_factors(self, energy=None, wavelength=None):
+    def scattering_factors(self, *, energy=None, wavelength=None):
         """
         X-ray scattering factors f', f''.
 
@@ -337,8 +335,7 @@ def f0(self, Q):
                                 charge=self.element.charge)
         return f
 
-    @require_keywords
-    def sld(self, wavelength=None, energy=None):
+    def sld(self, *, wavelength=None, energy=None):
         r"""
         X ray scattering length density.
 
@@ -382,8 +379,7 @@ def sld(self, wavelength=None, energy=None):
         return rho, irho
 
 # Note: docs and function prototype are reproduced in __init__
-@require_keywords
-def xray_sld(compound, density=None, natural_density=None,
+def xray_sld(compound, *, density=None, natural_density=None,
              wavelength=None, energy=None):
     """
     Compute xray scattering length densities for molecules.
@@ -435,8 +431,7 @@ def xray_sld(compound, density=None, natural_density=None,
     return rho, irho
 
 
-@require_keywords
-def index_of_refraction(compound, density=None, natural_density=None,
+def index_of_refraction(compound, *, density=None, natural_density=None,
                         energy=None, wavelength=None):
     """
     Calculates the index of refraction for a given compound
@@ -470,8 +465,7 @@ def index_of_refraction(compound, density=None, natural_density=None,
                       wavelength=wavelength)
     return 1 - wavelength**2/(2*pi)*(f1 + f2*1j)*1e-6
 
-@require_keywords
-def mirror_reflectivity(compound, density=None, natural_density=None,
+def mirror_reflectivity(compound, *, density=None, natural_density=None,
                         energy=None, wavelength=None,
                         angle=None, roughness=0):
     """