Merge branch 'develop' into feat/objectify-ccxt

freqtrade/strategy/resolver.py

@@ -0,0 +1,130 @@
+# pragma pylint: disable=attribute-defined-outside-init
+
+"""
+This module load custom strategies
+"""
+import importlib.util
+import inspect
+import logging
+import os
+from collections import OrderedDict
+from typing import Optional, Dict, Type
+
+from freqtrade import constants
+from freqtrade.strategy.interface import IStrategy
+
+
+logger = logging.getLogger(__name__)
+
+
+class StrategyResolver(object):
+    """
+    This class contains all the logic to load custom strategy class
+    """
+
+    __slots__ = ['strategy']
+
+    def __init__(self, config: Optional[Dict] = None) -> None:
+        """
+        Load the custom class from config parameter
+        :param config: configuration dictionary or None
+        """
+        config = config or {}
+
+        # Verify the strategy is in the configuration, otherwise fallback to the default strategy
+        strategy_name = config.get('strategy') or constants.DEFAULT_STRATEGY
+        self.strategy = self._load_strategy(strategy_name, extra_dir=config.get('strategy_path'))
+
+        # Set attributes
+        # Check if we need to override configuration
+        if 'minimal_roi' in config:
+            self.strategy.minimal_roi = config['minimal_roi']
+            logger.info("Override strategy \'minimal_roi\' with value in config file.")
+
+        if 'stoploss' in config:
+            self.strategy.stoploss = config['stoploss']
+            logger.info(
+                "Override strategy \'stoploss\' with value in config file: %s.", config['stoploss']
+            )
+
+        if 'ticker_interval' in config:
+            self.strategy.ticker_interval = config['ticker_interval']
+            logger.info(
+                "Override strategy \'ticker_interval\' with value in config file: %s.",
+                config['ticker_interval']
+            )
+
+        # Sort and apply type conversions
+        self.strategy.minimal_roi = OrderedDict(sorted(
+            {int(key): value for (key, value) in self.strategy.minimal_roi.items()}.items(),
+            key=lambda t: t[0]))
+        self.strategy.stoploss = float(self.strategy.stoploss)
+
+    def _load_strategy(
+            self, strategy_name: str, extra_dir: Optional[str] = None) -> Optional[IStrategy]:
+        """
+        Search and loads the specified strategy.
+        :param strategy_name: name of the module to import
+        :param extra_dir: additional directory to search for the given strategy
+        :return: Strategy instance or None
+        """
+        current_path = os.path.dirname(os.path.realpath(__file__))
+        abs_paths = [
+            os.path.join(current_path, '..', '..', 'user_data', 'strategies'),
+            current_path,
+        ]
+
+        if extra_dir:
+            # Add extra strategy directory on top of search paths
+            abs_paths.insert(0, extra_dir)
+
+        for path in abs_paths:
+            strategy = self._search_strategy(path, strategy_name)
+            if strategy:
+                logger.info('Using resolved strategy %s from \'%s\'', strategy_name, path)
+                return strategy
+
+        raise ImportError(
+            "Impossible to load Strategy '{}'. This class does not exist"
+            " or contains Python code errors".format(strategy_name)
+        )
+
+    @staticmethod
+    def _get_valid_strategies(module_path: str, strategy_name: str) -> Optional[Type[IStrategy]]:
+        """
+        Returns a list of all possible strategies for the given module_path
+        :param module_path: absolute path to the module
+        :param strategy_name: Class name of the strategy
+        :return: Tuple with (name, class) or None
+        """
+
+        # Generate spec based on absolute path
+        spec = importlib.util.spec_from_file_location('user_data.strategies', module_path)
+        module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(module)
+
+        valid_strategies_gen = (
+            obj for name, obj in inspect.getmembers(module, inspect.isclass)
+            if strategy_name == name and IStrategy in obj.__bases__
+        )
+        return next(valid_strategies_gen, None)
+
+    @staticmethod
+    def _search_strategy(directory: str, strategy_name: str) -> Optional[IStrategy]:
+        """
+        Search for the strategy_name in the given directory
+        :param directory: relative or absolute directory path
+        :return: name of the strategy class
+        """
+        logger.debug('Searching for strategy %s in \'%s\'', strategy_name, directory)
+        for entry in os.listdir(directory):
+            # Only consider python files
+            if not entry.endswith('.py'):
+                logger.debug('Ignoring %s', entry)
+                continue
+            strategy = StrategyResolver._get_valid_strategies(
+                os.path.abspath(os.path.join(directory, entry)), strategy_name
+            )
+            if strategy:
+                return strategy()
+        return None