diff --git a/examples/square.py b/examples/square.py
index 580df113f33af5743bc32140a460aba003aa6ca8..abad6392dbbc4e854acae37762b3f91f7290b712 100644
--- a/examples/square.py
+++ b/examples/square.py
@@ -10,7 +10,7 @@ from kwant.physics.leads import square_selfenergy
__all__ = ['System']
-class Lead(object):
+class Lead:
def __init__(self, width, t, potential):
self.width = width
self.t = t
diff --git a/kwant/builder.py b/kwant/builder.py
index 42ef1b11ff0fbc80f23fbdbb8749580f452193b8..faf37135090897feff18d3cb2841575613635ca9 100644
--- a/kwant/builder.py
+++ b/kwant/builder.py
@@ -82,7 +82,7 @@ class Site(tuple):
return self.family.pos(self.tag)
-class SiteFamily(object, metaclass=abc.ABCMeta):
+class SiteFamily(metaclass=abc.ABCMeta):
"""Abstract base class for site families.
Site families are the 'type' of `Site` objects. Within a family, individual
@@ -221,7 +221,7 @@ def validate_hopping(hopping):
################ Symmetries
-class Symmetry(object, metaclass=abc.ABCMeta):
+class Symmetry(metaclass=abc.ABCMeta):
"""Abstract base class for spatial symmetries.
Many physical systems possess a discrete spatial symmetry, which results in
@@ -321,7 +321,7 @@ class NoSymmetry(Symmetry):
################ Hopping kinds
-class HoppingKind(object):
+class HoppingKind:
"""A pattern for matching hoppings.
A hopping ``(a, b)`` matches precisely when the site family of ``a`` equals
@@ -413,7 +413,7 @@ def herm_conj(value):
return value
-class HermConjOfFunc(object):
+class HermConjOfFunc:
"""Proxy returning the hermitian conjugate of the original result."""
__slots__ = ('function')
@@ -426,7 +426,7 @@ class HermConjOfFunc(object):
################ Leads
-class Lead(object, metaclass=abc.ABCMeta):
+class Lead(metaclass=abc.ABCMeta):
"""Abstract base class for leads that can be attached to a `Builder`.
To attach a lead to a builder, append it to the builder's `~Builder.leads`
@@ -554,7 +554,7 @@ class ModesLead(Lead):
# A marker, meaning for hopping (i, j): this value is given by the Hermitian
# conjugate the value of the hopping (j, i). Used by Builder and System.
-class Other(object):
+class Other:
pass
@@ -567,7 +567,7 @@ def edges(seq):
return result
-class Builder(object):
+class Builder:
"""A tight binding system defined on a graph.
This is one of the central types in Kwant. It is used to construct tight
diff --git a/kwant/lattice.py b/kwant/lattice.py
index f00647d1d529dc1834e9590ea5c71b392d6a603a..9b26bca8d2ac096ce68e8b3914062bb63ee73f9c 100644
--- a/kwant/lattice.py
+++ b/kwant/lattice.py
@@ -49,7 +49,7 @@ def general(prim_vecs, basis=None, name=''):
return Polyatomic(prim_vecs, basis, name=name)
-class Polyatomic(object):
+class Polyatomic:
"""
A Bravais lattice with an arbitrary number of sites in the basis.
diff --git a/kwant/linalg/mumps.py b/kwant/linalg/mumps.py
index cd28860a17fb83145f91e290d1e5d3315913a337..0fa797bc00d14b172071e9a306c752e51ae1b156 100644
--- a/kwant/linalg/mumps.py
+++ b/kwant/linalg/mumps.py
@@ -86,7 +86,7 @@ class MUMPSError(RuntimeError):
RuntimeError.__init__(self, msg)
-class AnalysisStatistics(object):
+class AnalysisStatistics:
def __init__(self, inst, time=None):
self.est_mem_incore = inst.infog[17]
self.est_mem_ooc = inst.infog[27]
@@ -110,7 +110,7 @@ class AnalysisStatistics(object):
return " ".join(parts)
-class FactorizationStatistics(object):
+class FactorizationStatistics:
def __init__(self, inst, time=None, include_ordering=False):
# information about pivoting
self.offdiag_pivots = inst.infog[12] if inst.sym == 0 else 0
@@ -144,7 +144,7 @@ class FactorizationStatistics(object):
return " ".join(parts)
-class MUMPSContext(object):
+class MUMPSContext:
"""MUMPSContext contains the internal data structures needed by the
MUMPS library and contains a user-friendly interface.
diff --git a/kwant/physics/dispersion.py b/kwant/physics/dispersion.py
index 238f584cdc8237ecef88551db6f7955fe6e6806f..1dfff843daa09c457747eb7911367e4b3348e871 100644
--- a/kwant/physics/dispersion.py
+++ b/kwant/physics/dispersion.py
@@ -14,7 +14,7 @@ from .._common import ensure_isinstance
__all__ = ['Bands']
-class Bands(object):
+class Bands:
"""
Class of callable objects for the computation of energy bands.
diff --git a/kwant/physics/leads.py b/kwant/physics/leads.py
index edacd0bfb58110f1fc40cb9d7a4c46ce42350094..4342316e103967a24736b26fabe51063610f5e19 100644
--- a/kwant/physics/leads.py
+++ b/kwant/physics/leads.py
@@ -37,7 +37,7 @@ else:
Linsys = namedtuple('Linsys', ['eigenproblem', 'v', 'extract'])
-class PropagatingModes(object):
+class PropagatingModes:
"""The calculated propagating modes of a lead.
Attributes
@@ -68,7 +68,7 @@ class PropagatingModes(object):
self.__dict__.update(kwargs)
-class StabilizedModes(object):
+class StabilizedModes:
"""Stabilized eigendecomposition of the translation operator.
Due to the lack of Hermiticity of the translation operator, its
diff --git a/kwant/solvers/common.py b/kwant/solvers/common.py
index 6d6a683c8fce686af12693e18384f8b39d6c3311..a91d7c94aaffb029107128ba64020d2f0ca96a7e 100644
--- a/kwant/solvers/common.py
+++ b/kwant/solvers/common.py
@@ -29,7 +29,7 @@ from functools import reduce
LinearSys = namedtuple('LinearSys', ['lhs', 'rhs', 'indices', 'num_orb'])
-class SparseSolver(object, metaclass=abc.ABCMeta):
+class SparseSolver(metaclass=abc.ABCMeta):
"""Solver class for computing physical quantities based on solving
a liner system of equations.
@@ -546,7 +546,7 @@ class SparseSolver(object, metaclass=abc.ABCMeta):
return WaveFunction(self, sys, energy, args, check_hermiticity)
-class WaveFunction(object):
+class WaveFunction:
def __init__(self, solver, sys, energy, args, check_hermiticity):
ensure_isinstance(sys, system.System)
for lead in sys.leads:
@@ -568,7 +568,7 @@ class WaveFunction(object):
return result.transpose()
-class BlockResult(object, metaclass=abc.ABCMeta):
+class BlockResult(metaclass=abc.ABCMeta):
"""
ABC for a linear system solution with variable grouping.
"""
diff --git a/kwant/solvers/tests/_test_sparse.py b/kwant/solvers/tests/_test_sparse.py
index 3c26d263be9fae52e85fba704318e91331bf5130..380229a77f9cef5973663317fc5c21622d42f8ba 100644
--- a/kwant/solvers/tests/_test_sparse.py
+++ b/kwant/solvers/tests/_test_sparse.py
@@ -18,7 +18,7 @@ chain = kwant.lattice.chain()
sq = square = kwant.lattice.square()
-class LeadWithOnlySelfEnergy(object):
+class LeadWithOnlySelfEnergy:
def __init__(self, lead):
self.lead = lead
diff --git a/kwant/system.py b/kwant/system.py
index ca541b4ad9c832d3971b75fe61afe707b7e27230..5efbc5c80e1e660d3647487203a6d5ba54051c48 100644
--- a/kwant/system.py
+++ b/kwant/system.py
@@ -16,7 +16,7 @@ from copy import copy
from . import _system
-class System(object, metaclass=abc.ABCMeta):
+class System(metaclass=abc.ABCMeta):
"""Abstract general low-level system.
Attributes
@@ -225,7 +225,7 @@ class InfiniteSystem(System, metaclass=abc.ABCMeta):
return physics.selfenergy(ham, self.inter_cell_hopping(args))
-class PrecalculatedLead(object):
+class PrecalculatedLead:
def __init__(self, modes=None, selfenergy=None):
"""A general lead defined by its self energy.