stable/freqtrade/resolvers/iresolver.py
2019-03-15 19:50:38 +01:00

66 lines
2.3 KiB
Python

# pragma pylint: disable=attribute-defined-outside-init
"""
This module load custom objects
"""
import importlib.util
import inspect
import logging
from pathlib import Path
from typing import Optional, Type, Any
logger = logging.getLogger(__name__)
class IResolver(object):
"""
This class contains all the logic to load custom classes
"""
@staticmethod
def _get_valid_object(object_type, module_path: Path,
object_name: str) -> Optional[Type[Any]]:
"""
Returns the first object with matching object_type and object_name in the path given.
:param object_type: object_type (class)
:param module_path: absolute path to the module
:param object_name: Class name of the object
:return: class or None
"""
# Generate spec based on absolute path
spec = importlib.util.spec_from_file_location('unknown', str(module_path))
module = importlib.util.module_from_spec(spec)
try:
spec.loader.exec_module(module) # type: ignore # importlib does not use typehints
except (ModuleNotFoundError, SyntaxError) as err:
# Catch errors in case a specific module is not installed
logger.warning(f"Could not import {module_path} due to '{err}'")
valid_objects_gen = (
obj for name, obj in inspect.getmembers(module, inspect.isclass)
if object_name == name and object_type in obj.__bases__
)
return next(valid_objects_gen, None)
@staticmethod
def _search_object(directory: Path, object_type, object_name: str,
kwargs: dict = {}) -> Optional[Any]:
"""
Search for the objectname in the given directory
:param directory: relative or absolute directory path
:return: object instance
"""
logger.debug("Searching for %s %s in '%s'", object_type.__name__, object_name, directory)
for entry in directory.iterdir():
# Only consider python files
if not str(entry).endswith('.py'):
logger.debug('Ignoring %s', entry)
continue
obj = IResolver._get_valid_object(
object_type, Path.resolve(directory.joinpath(entry)), object_name
)
if obj:
return obj(**kwargs)
return None