create exchange_resolver

freqtrade/resolvers/exchange_resolver.py

@@ -0,0 +1,57 @@
+"""
+This module loads custom exchanges
+"""
+import logging
+from pathlib import Path
+
+from freqtrade.exchange import Exchange
+from freqtrade.resolvers import IResolver
+
+logger = logging.getLogger(__name__)
+
+
+class ExchangeResolver(IResolver):
+    """
+    This class contains all the logic to load a custom exchange class
+    """
+
+    __slots__ = ['exchange']
+
+    def __init__(self, exchange_name: str, freqtrade, config: dict) -> None:
+        """
+        Load the custom class from config parameter
+        :param config: configuration dictionary or None
+        """
+        self.pairlist = self._load_exchange(exchange_name, kwargs={'freqtrade': freqtrade,
+                                                                   'config': config})
+
+    def _load_exchange(
+            self, exchange_name: str, kwargs: dict) -> Exchange:
+        """
+        Search and loads the specified exchange.
+        :param exchange_name: name of the module to import
+        :param extra_dir: additional directory to search for the given exchange
+        :return: Exchange instance or None
+        """
+        current_path = Path(__file__).parent.parent.joinpath('exchange').resolve()
+
+        abs_paths = [
+            current_path.parent.parent.joinpath('user_data/exchange'),
+            current_path,
+        ]
+
+        for _path in abs_paths:
+            try:
+                pairlist = self._search_object(directory=_path, object_type=Exchange,
+                                               object_name=exchange_name,
+                                               kwargs=kwargs)
+                if pairlist:
+                    logger.info('Using resolved exchange %s from \'%s\'', exchange_name, _path)
+                    return pairlist
+            except FileNotFoundError:
+                logger.warning('Path "%s" does not exist', _path.relative_to(Path.cwd()))
+
+        raise ImportError(
+            "Impossible to load Exchange '{}'. This class does not exist"
+            " or contains Python code errors".format(exchange_name)
+        )