#----------------------------------------------------------------------------- # Copyright (c) 2012 - 2020, Anaconda, Inc., and Bokeh Contributors. # All rights reserved. # # The full license is in the file LICENSE.txt, distributed with this software. #----------------------------------------------------------------------------- ''' Utilities for checking dependencies ''' #----------------------------------------------------------------------------- # Boilerplate #----------------------------------------------------------------------------- import logging # isort:skip log = logging.getLogger(__name__) #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- # Standard library imports from importlib import import_module from types import ModuleType from typing import Optional #----------------------------------------------------------------------------- # Globals and constants #----------------------------------------------------------------------------- __all__ = ( 'import_optional', 'import_required', ) #----------------------------------------------------------------------------- # General API #----------------------------------------------------------------------------- [docs]def import_optional(mod_name: str) -> Optional[ModuleType]: ''' Attempt to import an optional dependency. Silently returns None if the requested module is not available. Args: mod_name (str) : name of the optional module to try to import Returns: imported module or None, if import fails ''' try: return import_module(mod_name) except ImportError: pass except Exception: msg = "Failed to import optional module `{}`".format(mod_name) log.exception(msg) return None [docs]def import_required(mod_name: str, error_msg: str) -> ModuleType: ''' Attempt to import a required dependency. Raises a RuntimeError if the requested module is not available. Args: mod_name (str) : name of the required module to try to import error_msg (str) : error message to raise when the module is missing Returns: imported module Raises: RuntimeError ''' try: return import_module(mod_name) except ImportError as e: raise RuntimeError(error_msg) from e #----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------