stable/freqtrade/resolvers/iresolver.py

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# pragma pylint: disable=attribute-defined-outside-init
"""
This module load custom objects
"""
import importlib.util
import inspect
import logging
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from pathlib import Path
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from typing import Any, Dict, Generator, List, Optional, Tuple, Type, Union
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from freqtrade import OperationalException
logger = logging.getLogger(__name__)
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class IResolver:
"""
This class contains all the logic to load custom classes
"""
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# Childclasses need to override this
object_type: Type[Any]
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object_type_str: str
user_subdir: Optional[str] = None
initial_search_path: Path
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@classmethod
def build_search_paths(cls, config, user_subdir: Optional[str] = None,
extra_dir: Optional[str] = None) -> List[Path]:
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abs_paths: List[Path] = [cls.initial_search_path]
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if user_subdir:
abs_paths.insert(0, config['user_data_dir'].joinpath(user_subdir))
if extra_dir:
# Add extra directory to the top of the search paths
abs_paths.insert(0, Path(extra_dir).resolve())
return abs_paths
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@classmethod
def _get_valid_object(cls, module_path: Path,
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object_name: Optional[str]) -> Generator[Any, None, None]:
"""
Generator returning objects with matching object_type and object_name in the path given.
:param module_path: absolute path to the module
:param object_name: Class name of the object
:return: generator containing matching objects
"""
# Generate spec based on absolute path
# Pass object_name as first argument to have logging print a reasonable name.
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spec = importlib.util.spec_from_file_location(object_name or "", str(module_path))
module = importlib.util.module_from_spec(spec)
try:
spec.loader.exec_module(module) # type: ignore # importlib does not use typehints
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except (ModuleNotFoundError, SyntaxError) as err:
# Catch errors in case a specific module is not installed
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logger.warning(f"Could not import {module_path} due to '{err}'")
valid_objects_gen = (
obj for name, obj in inspect.getmembers(module, inspect.isclass)
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if (object_name is None or object_name == name) and cls.object_type in obj.__bases__
)
return valid_objects_gen
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@classmethod
def _search_object(cls, directory: Path, object_name: str
) -> Union[Tuple[Any, Path], Tuple[None, None]]:
"""
Search for the objectname in the given directory
:param directory: relative or absolute directory path
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:param object_name: ClassName of the object to load
:return: object class
"""
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logger.debug(f"Searching for {cls.object_type.__name__} {object_name} in '{directory}'")
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for entry in directory.iterdir():
# Only consider python files
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if not str(entry).endswith('.py'):
logger.debug('Ignoring %s', entry)
continue
module_path = entry.resolve()
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obj = next(cls._get_valid_object(module_path, object_name), None)
if obj:
return (obj, module_path)
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return (None, None)
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@classmethod
def _load_object(cls, paths: List[Path], object_name: str,
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kwargs: dict = {}) -> Optional[Any]:
"""
Try to load object from path list.
"""
for _path in paths:
try:
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(module, module_path) = cls._search_object(directory=_path,
object_name=object_name)
if module:
logger.info(
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f"Using resolved {cls.object_type.__name__.lower()[1:]} {object_name} "
f"from '{module_path}'...")
return module(**kwargs)
except FileNotFoundError:
logger.warning('Path "%s" does not exist.', _path.resolve())
return None
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@classmethod
def load_object(cls, object_name: str, config: dict, kwargs: dict,
extra_dir: Optional[str] = None) -> Any:
"""
Search and loads the specified object as configured in hte child class.
:param objectname: name of the module to import
:param config: configuration dictionary
:param extra_dir: additional directory to search for the given pairlist
:raises: OperationalException if the class is invalid or does not exist.
:return: Object instance or None
"""
abs_paths = cls.build_search_paths(config,
user_subdir=cls.user_subdir,
extra_dir=extra_dir)
pairlist = cls._load_object(paths=abs_paths, object_name=object_name,
kwargs=kwargs)
if pairlist:
return pairlist
raise OperationalException(
f"Impossible to load {cls.object_type_str} '{object_name}'. This class does not exist "
"or contains Python code errors."
)
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@classmethod
def search_all_objects(cls, directory: Path) -> List[Dict[str, Any]]:
"""
Searches a directory for valid objects
:param directory: Path to search
:return: List of dicts containing 'name', 'class' and 'location' entires
"""
logger.debug(f"Searching for {cls.object_type.__name__} '{directory}'")
objects = []
for entry in directory.iterdir():
# Only consider python files
if not str(entry).endswith('.py'):
logger.debug('Ignoring %s', entry)
continue
module_path = entry.resolve()
logger.debug(f"Path {module_path}")
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for obj in cls._get_valid_object(module_path, object_name=None):
objects.append(
{'name': obj.__name__,
'class': obj,
'location': entry,
})
return objects