Replace old format string interpolation with f-strings (#579)

Since Python 3.5 is no longer supported, format string interpolations
can now be replaced by f-strings, introduced in Python 3.6, which are
more readable, require less characters and are more efficient.

Note that `pylint` issues a warning when using f-strings for log
messages, just as it does for format interpolated strings. The reasoning
is that this is slightly inefficient as the strings are always
interpolated even if the log is discarded, but also by not passing the
formatting parameters as arguments, the available metadata is reduced.
I feel these inefficiencies are premature optimizations as they are
really minimal and don't weigh up against the improved readability and
maintainability of using f-strings. That is why the `pylint` config is
update to ignore the warning `logging-fstring-interpolation` which
replaces `logging-format-interpolation` that was ignored before.

The majority of the conversions were done automatically with the linting
tool `flynt` which is also added as a pre-commit hook. It is added
before the `yapf` step because since `flynt` will touch formatting,
`yapf` will then get a chance to check it.

.pre-commit-config.yaml

@@ -13,6 +13,15 @@ repos:
  tests/.*.in$
  )$
 
+- repo: https://github.com/ikamensh/flynt/
+ rev: '0.55'
+ hooks:
+ - id: flynt
+ args: [
+ '--line-length=120',
+ '--fail-on-change',
+ ]
+
 - repo: https://github.com/PyCQA/pydocstyle
  rev: 5.0.2
  hooks:

aiida_quantumespresso/calculations/__init__.py

@@ -6,7 +6,6 @@
 from aiida import orm
 from aiida.common import datastructures, exceptions
 from aiida.common.lang import classproperty
-
 from qe_tools.converters import get_parameters_from_cell
 
 from aiida_quantumespresso.utils.convert import convert_input_to_namelist_entry
@@ -163,7 +162,7 @@ def prepare_for_submission(self, folder):
 
  # Create an `.EXIT` file if `only_initialization` flag in `settings` is set to `True`
  if settings.pop('ONLY_INITIALIZATION', False):
- with folder.open('{}.EXIT'.format(self._PREFIX), 'w') as handle:
+ with folder.open(f'{self._PREFIX}.EXIT', 'w') as handle:
  handle.write('\n')
 
  # Check if specific inputs for the ENVIRON module where specified
@@ -240,7 +239,7 @@ def prepare_for_submission(self, folder):
 
  if settings:
  unknown_keys = ', '.join(list(settings.keys()))
- raise exceptions.InputValidationError('`settings` contained unexpected keys: {}'.format(unknown_keys))
+ raise exceptions.InputValidationError(f'`settings` contained unexpected keys: {unknown_keys}')
 
  return calcinfo
 
@@ -332,7 +331,7 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
  )
 
  kind_names.append(kind.name)
- atomic_species_card_list.append('{} {} {}\n'.format(kind.name.ljust(6), kind.mass, filename))
+ atomic_species_card_list.append(f'{kind.name.ljust(6)} {kind.mass} {filename}\n')
 
  # I join the lines, but I resort them using the alphabetical order of
  # species, given by the kind_names list. I also store the mapping_species
@@ -370,13 +369,11 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
  for i, this_atom_fix in enumerate(fixed_coords):
  if len(this_atom_fix) != 3:
  raise exceptions.InputValidationError(
- 'fixed_coords({:d}) has not length three'
- ''.format(i + 1))
+ f'fixed_coords({i + 1:d}) has not length three')
  for fixed_c in this_atom_fix:
  if not isinstance(fixed_c, bool):
  raise exceptions.InputValidationError(
- 'fixed_coords({:d}) has non-boolean '
- 'elements'.format(i + 1))
+ f'fixed_coords({i + 1:d}) has non-boolean elements')
 
  if_pos_values = [cls._if_pos(_) for _ in this_atom_fix]
  fixed_coords_strings.append(
@@ -418,7 +415,7 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
 
  # Checking that all 3 dimensions are specified:
  if len(vector) != 3:
- raise exceptions.InputValidationError('Forces({}) for {} has not length three'.format(vector, site))
+ raise exceptions.InputValidationError(f'Forces({vector}) for {site} has not length three')
 
  lines.append('{0} {1:18.10f} {2:18.10f} {3:18.10f}\n'.format(site.kind_name.ljust(6), *vector))
 
@@ -444,7 +441,7 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
  # Checking that all 3 dimensions are specified:
  if len(vector) != 3:
  raise exceptions.InputValidationError(
- 'Velocities({}) for {} has not length three'.format(vector, site)
+ f'Velocities({vector}) for {site} has not length three'
  )
 
  lines.append('{0} {1:18.10f} {2:18.10f} {3:18.10f}\n'.format(site.kind_name.ljust(6), *vector))
@@ -467,7 +464,7 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
  tolerance=settings.pop('IBRAV_CELL_TOLERANCE', 1e-6)
  )
  except ValueError as exc:
- raise QEInputValidationError('Cannot get structure parameters from cell: {}'.format(exc)) from exc
+ raise QEInputValidationError(f'Cannot get structure parameters from cell: {exc}') from exc
  input_params['SYSTEM'].update(structure_parameters)
  input_params['SYSTEM']['nat'] = len(structure.sites)
  input_params['SYSTEM']['ntyp'] = len(structure.kinds)
@@ -526,7 +523,7 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
  else:
  kpoints_type = 'crystal'
 
- kpoints_card_list = ['K_POINTS {}\n'.format(kpoints_type)]
+ kpoints_card_list = [f'K_POINTS {kpoints_type}\n']
 
  if kpoints_type == 'automatic':
  if any([i not in [0, 0.5] for i in offset]):
@@ -540,11 +537,10 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
  # nothing to be written in this case
  pass
  else:
- kpoints_card_list.append('{:d}\n'.format(num_kpoints))
+ kpoints_card_list.append(f'{num_kpoints:d}\n')
  for kpoint, weight in zip(kpoints_list, weights):
  kpoints_card_list.append(
- ' {:18.10f} {:18.10f} {:18.10f} {:18.10f}'
- '\n'.format(kpoint[0], kpoint[1], kpoint[2], weight))
+ f' {kpoint[0]:18.10f} {kpoint[1]:18.10f} {kpoint[2]:18.10f} {weight:18.10f}\n')
 
  kpoints_card = ''.join(kpoints_card_list)
  del kpoints_card_list
@@ -577,7 +573,7 @@ def _generate_PWCPinputdata(cls, parameters, settings, pseudos, structure, kpoin
 
  inputfile = ''
  for namelist_name in namelists_toprint:
- inputfile += '&{0}\n'.format(namelist_name)
+ inputfile += f'&{namelist_name}\n'
  # namelist content; set to {} if not present, so that we leave an empty namelist
  namelist = input_params.pop(namelist_name, {})
  for key, value in sorted(namelist.items()):
@@ -623,7 +619,7 @@ def _case_transform_dict(dictionary, dict_name, func_name, transform):
  from collections import Counter
 
  if not isinstance(dictionary, dict):
- raise TypeError('{} accepts only dictionaries as argument, got {}'.format(func_name, type(dictionary)))
+ raise TypeError(f'{func_name} accepts only dictionaries as argument, got {type(dictionary)}')
  new_dict = dict((transform(str(k)), v) for k, v in dictionary.items())
  if len(new_dict) != len(dictionary):
  num_items = Counter(transform(str(k)) for k in dictionary.keys())

aiida_quantumespresso/calculations/cp.py

@@ -31,7 +31,7 @@ class CpCalculation(BasePwCpInputGenerator):
  _FILE_XML_PRINT_COUNTER_BASENAME = 'print_counter.xml'
  _FILE_XML_PRINT_COUNTER = os.path.join(
  BasePwCpInputGenerator._OUTPUT_SUBFOLDER,
- '{}_{}.save'.format(BasePwCpInputGenerator._PREFIX, _CP_WRITE_UNIT_NUMBER),
+ f'{BasePwCpInputGenerator._PREFIX}_{_CP_WRITE_UNIT_NUMBER}.save',
  _FILE_XML_PRINT_COUNTER_BASENAME,
  )
 
@@ -90,20 +90,20 @@ class CpCalculation(BasePwCpInputGenerator):
  _internal_retrieve_list = [
  os.path.join(
  BasePwCpInputGenerator._OUTPUT_SUBFOLDER,
- '{}.{}'.format(BasePwCpInputGenerator._PREFIX, ext),
+ f'{BasePwCpInputGenerator._PREFIX}.{ext}',
  ) for ext in _cp_ext_list
  ] + [_FILE_XML_PRINT_COUNTER]
 
  # in restarts, it will copy from the parent the following
  _restart_copy_from = os.path.join(
  BasePwCpInputGenerator._OUTPUT_SUBFOLDER,
- '{}_{}.save'.format(BasePwCpInputGenerator._PREFIX, _CP_WRITE_UNIT_NUMBER),
+ f'{BasePwCpInputGenerator._PREFIX}_{_CP_WRITE_UNIT_NUMBER}.save',
  )
 
  # in restarts, it will copy the previous folder in the following one
  _restart_copy_to = os.path.join(
  BasePwCpInputGenerator._OUTPUT_SUBFOLDER,
- '{}_{}.save'.format(BasePwCpInputGenerator._PREFIX, _CP_READ_UNIT_NUMBER),
+ f'{BasePwCpInputGenerator._PREFIX}_{_CP_READ_UNIT_NUMBER}.save',
  )
 
  @classproperty
@@ -115,7 +115,7 @@ def xml_filepaths(cls):
  for filename in cls.xml_filenames:
  filepath = os.path.join(
  cls._OUTPUT_SUBFOLDER,
- '{}_{}.save'.format(cls._PREFIX, cls._CP_WRITE_UNIT_NUMBER),
+ f'{cls._PREFIX}_{cls._CP_WRITE_UNIT_NUMBER}.save',
  filename,
  )
  filepaths.append(filepath)

aiida_quantumespresso/calculations/epw.py

@@ -86,7 +86,7 @@ def test_offset(offset):
  parent_calc_nscf = parent_folder_nscf.creator
 
  if parent_calc_nscf is None:
- raise exceptions.NotExistent('parent_folder<{}> has no parent calculation'.format(parent_folder_nscf.pk))
+ raise exceptions.NotExistent(f'parent_folder<{parent_folder_nscf.pk}> has no parent calculation')
 
  # Also, the parent calculation must be on the same computer
  if not self.node.computer.uuid == parent_calc_nscf.computer.uuid:
@@ -188,13 +188,13 @@ def test_offset(offset):
 
  # add here the list of point coordinates
  if len(list_of_points) > 1:
- postpend_text = '{} cartesian\n'.format(len(list_of_points))
+ postpend_text = f'{len(list_of_points)} cartesian\n'
  for points in list_of_points:
  postpend_text += '{0:18.10f} {1:18.10f} {2:18.10f} \n'.format(*points)
 
  with folder.open(self.metadata.options.input_filename, 'w') as infile:
  for namelist_name in namelists_toprint:
- infile.write('&{0}\n'.format(namelist_name))
+ infile.write(f'&{namelist_name}\n')
  # namelist content; set to {} if not present, so that we leave an empty namelist
  namelist = parameters.pop(namelist_name, {})
  for key, value in sorted(namelist.items()):
@@ -282,6 +282,6 @@ def test_offset(offset):
 
  if settings:
  unknown_keys = ', '.join(list(settings.keys()))
- raise exceptions.InputValidationError('`settings` contained unexpected keys: {}'.format(unknown_keys))
+ raise exceptions.InputValidationError(f'`settings` contained unexpected keys: {unknown_keys}')
 
  return calcinfo