Adopt lazy imports from Terra

qiskit_nature/drivers/second_quantization/electronic_structure_molecule_driver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2021.
+# (C) Copyright IBM 2021, 2022.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -81,7 +81,8 @@ def driver_class_from_type(
                 raise MissingOptionalLibraryError(
                     libname=driver_type, name="ElectronicStructureDriverType"
                 )
-            driver_class.check_installed()
+            # instantiating the object will check if the driver is installed
+            _ = driver_class()
             driver_class.check_method_supported(method)
 
         logger.debug("%s found from type %s.", driver_class.__name__, driver_type.value)

qiskit_nature/drivers/second_quantization/gaussiand/gaussian_forces_driver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2020, 2021.
+# (C) Copyright IBM 2020, 2022.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -18,10 +18,10 @@
 from qiskit_nature.properties.second_quantization.vibrational import (
     VibrationalStructureDriverResult,
 )
+import qiskit_nature.optionals as _optionals
 from ...units_type import UnitsType
 from ..vibrational_structure_driver import VibrationalStructureDriver
 from ...molecule import Molecule
-from .gaussian_utils import check_valid
 from .gaussian_log_driver import GaussianLogDriver
 from .gaussian_log_result import GaussianLogResult
 
@@ -75,9 +75,10 @@ def __init__(
         # If running from a jcf we need Gaussian™ 16 so check if we have a
         # valid install.
         if self._logfile is None:
-            check_valid()
+            _optionals.HAS_GAUSSIAN.require_now("GaussianForcesDriver __init__")
 
     @staticmethod
+    @_optionals.HAS_GAUSSIAN.require_in_call
     def from_molecule(
         molecule: Molecule,
         basis: str = "sto-3g",
@@ -98,7 +99,6 @@ def from_molecule(
         """
         # Ignore kwargs parameter for this driver
         del driver_kwargs
-        GaussianForcesDriver.check_installed()
         basis = GaussianForcesDriver.to_driver_basis(basis)
 
         if molecule.units == UnitsType.ANGSTROM:
@@ -130,16 +130,6 @@ def to_driver_basis(basis: str) -> str:
             return "sto-3g"
         return basis
 
-    @staticmethod
-    def check_installed() -> None:
-        """
-        Checks if Gaussian is installed and available
-
-        Raises:
-            MissingOptionalLibraryError: if not installed.
-        """
-        check_valid()
-
     def run(self) -> VibrationalStructureDriverResult:
         if self._logfile is not None:
             glr = GaussianLogResult(self._logfile)

qiskit_nature/drivers/second_quantization/gaussiand/gaussian_log_driver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2020, 2021.
+# (C) Copyright IBM 2020, 2022.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -16,14 +16,16 @@
 import logging
 
 from qiskit_nature import QiskitNatureError
+import qiskit_nature.optionals as _optionals
 
 from ..base_driver import BaseDriver
-from .gaussian_utils import check_valid, run_g16
+from .gaussian_utils import run_g16
 from .gaussian_log_result import GaussianLogResult
 
 logger = logging.getLogger(__name__)
 
 
+@_optionals.HAS_GAUSSIAN.require_in_instance
 class GaussianLogDriver(BaseDriver):
     """Gaussian™ 16 log driver.
 
@@ -47,8 +49,6 @@ def __init__(self, jcf: Union[str, List[str]]) -> None:
         Raises:
             QiskitNatureError: Invalid Input
         """
-        GaussianLogDriver.check_installed()
-
         if not isinstance(jcf, list) and not isinstance(jcf, str):
             raise QiskitNatureError(f"Invalid input for Gaussian Log Driver '{jcf}'")
 
@@ -58,16 +58,6 @@ def __init__(self, jcf: Union[str, List[str]]) -> None:
         self._jcf = jcf
         super().__init__()
 
-    @staticmethod
-    def check_installed() -> None:
-        """
-        Checks if Gaussian is installed and available
-
-        Raises:
-            MissingOptionalLibraryError: if not installed.
-        """
-        check_valid()
-
     def run(self) -> GaussianLogResult:  # type: ignore
         """Runs the driver to produce a result given the supplied job control file.
 

qiskit_nature/drivers/second_quantization/gaussiand/gaussian_utils.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2020, 2021.
+# (C) Copyright IBM 2020, 2022.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -14,32 +14,11 @@
 
 import logging
 from subprocess import Popen, PIPE
-from shutil import which
-from qiskit.exceptions import MissingOptionalLibraryError
 from qiskit_nature import QiskitNatureError
+import qiskit_nature.optionals as _optionals
 
 logger = logging.getLogger(__name__)
 
-_GAUSSIAN_16 = "g16"
-_GAUSSIAN_16_DESC = "Gaussian 16"
-
-_G16PROG = which(_GAUSSIAN_16)
-
-
-def check_valid() -> None:
-    """
-    Checks if Gaussian is installed and available
-
-    Raises:
-        MissingOptionalLibraryError: if not installed.
-    """
-    if _G16PROG is None:
-        raise MissingOptionalLibraryError(
-            libname=_GAUSSIAN_16,
-            name=_GAUSSIAN_16_DESC,
-            msg="Please check that it is installed correctly",
-        )
-
 
 def run_g16(cfg: str) -> str:
     """
@@ -58,14 +37,16 @@ def run_g16(cfg: str) -> str:
     """
     process = None
     try:
-        with Popen(_GAUSSIAN_16, stdin=PIPE, stdout=PIPE, universal_newlines=True) as process:
+        with Popen(
+            _optionals.GAUSSIAN_16, stdin=PIPE, stdout=PIPE, universal_newlines=True
+        ) as process:
             stdout, _ = process.communicate(cfg)
             process.wait()
     except Exception as ex:
         if process is not None:
             process.kill()
 
-        raise QiskitNatureError(f"{_GAUSSIAN_16_DESC} run has failed") from ex
+        raise QiskitNatureError(f"{_optionals.GAUSSIAN_16_DESC} run has failed") from ex
 
     if process.returncode != 0:
         errmsg = ""
@@ -78,7 +59,7 @@ def run_g16(cfg: str) -> str:
                 logger.error(lines[i])
                 errmsg += lines[i] + "\n"
         raise QiskitNatureError(
-            f"{_GAUSSIAN_16_DESC} process return code {process.returncode}\n{errmsg}"
+            f"{_optionals.GAUSSIAN_16_DESC} process return code {process.returncode}\n{errmsg}"
         )
 
     all_text = ""

qiskit_nature/drivers/second_quantization/gaussiand/gaussiandriver.py

@@ -25,9 +25,10 @@
 from qiskit_nature import QiskitNatureError
 from qiskit_nature.constants import PERIODIC_TABLE
 from qiskit_nature.properties.second_quantization.electronic import ElectronicStructureDriverResult
+import qiskit_nature.optionals as _optionals
 
 from ...qmolecule import QMolecule
-from .gaussian_utils import check_valid, run_g16
+from .gaussian_utils import run_g16
 from ..electronic_structure_driver import ElectronicStructureDriver, MethodType
 from ...molecule import Molecule
 from ...units_type import UnitsType
@@ -36,6 +37,7 @@
 logger = logging.getLogger(__name__)
 
 
+@_optionals.HAS_GAUSSIAN.require_in_instance
 class GaussianDriver(ElectronicStructureDriver):
     """
     Qiskit Nature driver using the Gaussian™ 16 program.
@@ -62,7 +64,6 @@ def __init__(
             QiskitNatureError: Invalid Input
         """
         super().__init__()
-        GaussianDriver.check_installed()
         if not isinstance(config, str) and not isinstance(config, list):
             raise QiskitNatureError(f"Invalid config for Gaussian Driver '{config}'")
 
@@ -72,6 +73,7 @@ def __init__(
         self._config = config
 
     @staticmethod
+    @_optionals.HAS_GAUSSIAN.require_in_call
     def from_molecule(
         molecule: Molecule,
         basis: str = "sto-3g",
@@ -91,7 +93,6 @@ def from_molecule(
         """
         # Ignore kwargs parameter for this driver
         del driver_kwargs
-        GaussianDriver.check_installed()
         GaussianDriver.check_method_supported(method)
         basis = GaussianDriver.to_driver_basis(basis)
 
@@ -124,16 +125,6 @@ def to_driver_basis(basis: str) -> str:
             return "sto-3g"
         return basis
 
-    @staticmethod
-    def check_installed() -> None:
-        """
-        Checks if Gaussian is installed and available
-
-        Raises:
-            MissingOptionalLibraryError: if not installed.
-        """
-        check_valid()
-
     @staticmethod
     def check_method_supported(method: MethodType) -> None:
         """

qiskit_nature/drivers/second_quantization/psi4d/psi4driver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2018, 2021.
+# (C) Copyright IBM 2018, 2022.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -19,12 +19,11 @@
 import tempfile
 import warnings
 from pathlib import Path
-from shutil import which
 from typing import Union, List, Optional, Any, Dict
 
-from qiskit.exceptions import MissingOptionalLibraryError
 from qiskit_nature import QiskitNatureError
 from qiskit_nature.properties.second_quantization.electronic import ElectronicStructureDriverResult
+import qiskit_nature.optionals as _optionals
 
 from ...qmolecule import QMolecule
 from ..electronic_structure_driver import ElectronicStructureDriver, MethodType
@@ -34,11 +33,8 @@
 
 logger = logging.getLogger(__name__)
 
-PSI4 = "psi4"
-
-PSI4_APP = which(PSI4)
-
 
+@_optionals.HAS_PSI4.require_in_instance
 class PSI4Driver(ElectronicStructureDriver):
     """
     Qiskit Nature driver using the PSI4 program.
@@ -61,7 +57,6 @@ def __init__(
             QiskitNatureError: Invalid Input
         """
         super().__init__()
-        PSI4Driver.check_installed()
         if not isinstance(config, str) and not isinstance(config, list):
             raise QiskitNatureError(f"Invalid config for PSI4 Driver '{config}'")
 
@@ -71,6 +66,7 @@ def __init__(
         self._config = config
 
     @staticmethod
+    @_optionals.HAS_PSI4.require_in_call
     def from_molecule(
         molecule: Molecule,
         basis: str = "sto3g",
@@ -91,7 +87,6 @@ def from_molecule(
         """
         # Ignore kwargs parameter for this driver
         del driver_kwargs
-        PSI4Driver.check_installed()
         PSI4Driver.check_method_supported(method)
         basis = PSI4Driver.to_driver_basis(basis)
 
@@ -124,17 +119,6 @@ def to_driver_basis(basis: str) -> str:
             return "sto-3g"
         return basis
 
-    @staticmethod
-    def check_installed() -> None:
-        """
-        Checks if PSI4 is installed and available
-
-        Raises:
-            MissingOptionalLibraryError: if not installed.
-        """
-        if PSI4_APP is None:
-            raise MissingOptionalLibraryError(libname="PSI4", name="PSI4Driver")
-
     @staticmethod
     def check_method_supported(method: MethodType) -> None:
         """
@@ -228,7 +212,7 @@ def _run_psi4(input_file, output_file):
         process = None
         try:
             with subprocess.Popen(
-                [PSI4, input_file, output_file],
+                [_optionals.PSI4, input_file, output_file],
                 stdout=subprocess.PIPE,
                 universal_newlines=True,
             ) as process:
@@ -238,7 +222,7 @@ def _run_psi4(input_file, output_file):
             if process is not None:
                 process.kill()
 
-            raise QiskitNatureError(f"{PSI4} run has failed") from ex
+            raise QiskitNatureError(f"{_optionals.PSI4} run has failed") from ex
 
         if process.returncode != 0:
             errmsg = ""
@@ -247,4 +231,6 @@ def _run_psi4(input_file, output_file):
                 for i, _ in enumerate(lines):
                     logger.error(lines[i])
                     errmsg += lines[i] + "\n"
-            raise QiskitNatureError(f"{PSI4} process return code {process.returncode}\n{errmsg}")
+            raise QiskitNatureError(
+                f"{_optionals.PSI4} process return code {process.returncode}\n{errmsg}"
+            )