Source code for BioSimSpace._Utils._module_stub

######################################################################
# BioSimSpace: Making biomolecular simulation a breeze!
#
# Copyright: 2017-2023
#
# Authors: Lester Hedges <lester.hedges@gmail.com>
#
# BioSimSpace is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# BioSimSpace is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with BioSimSpace. If not, see <http://www.gnu.org/licenses/>.
#####################################################################

"""
This file provides a class that can be used to stub any
module that BioSimSpace fails to import. The class will
raise a ModuleNotFound exception with a clear instruction
to the user if any attempt it made to use a module that
has not been installed.
"""

__author__ = "Christopher Woods"
__email__ = "chryswoods@hey.com"

__all__ = ["_module_stub", "_try_import", "_assert_imported", "_have_imported"]

_failed_modules = {}


class _ModuleStub:
    def __init__(self, name: str, install_command: str):
        self._name = name

        if install_command is None:
            self._install_command = f"conda install {name}"
        else:
            self._install_command = install_command

    def __repr__(self):
        return f"<stubmodule '{self._name}' from /could/not/be/imported>"

    def __getattr__(self, key):
        import BioSimSpace

        message = (
            f"Cannot continue as the module '{self._name}' "
            "has not been installed. To continue, you "
            "should install the module using the command "
            f"'{self._install_command}'."
        )

        if BioSimSpace._isVerbose():
            print(message)

        raise ModuleNotFoundError(message)


[docs] def _module_stub(name: str, install_command: str = None): """ Return a ModuleStub that will raise a ModuleNotFoundError if it is used in any way. Parameters ---------- name : str The name of the module being stubbed install_command : str (optional) The command used to install the module. If this is not supplied, then it is assumed to be 'conda install {name}' Returns ------- module : _ModuleStub The stubbed module """ return _ModuleStub(name=name, install_command=install_command)
[docs] def _try_import(name: str, install_command: str = None): """ Try to import the module called 'name' and return the resulting module. If this fails, catch the error and instead return a _ModuleStub. Parameters ---------- name : str The name of the module being stubbed install_command : str (optional) The command used to install the module. If this is not supplied, then it is assumed to be 'conda install {name}' Returns ------- module : _ModuleStub | module The module if it loaded correctly, else otherwise a _ModuleStub for that module """ global _failed_modules if name in _failed_modules: return _failed_modules[name] import importlib try: m = importlib.import_module(name) except Exception as e: m = _ModuleStub(name=name, install_command=install_command) _failed_modules[name] = m import BioSimSpace if BioSimSpace._isVerbose(): print(f"Failed to import module {name}.") print("Functionality that depends on this module will " "not be available.") return m
[docs] def _assert_imported(module): """ Assert that the passed module has indeed been imported. This will raise a ModuleNotFoundError if the module has not been imported, and has instead been stubbed. """ if type(module) == _ModuleStub: module.this_will_break()
[docs] def _have_imported(module) -> bool: """ Return whether or not the passed module has indeed been imported (and thus is not stubbed). """ return type(module) != _ModuleStub