From 5fefa9e97c01b83accd9ddd8c44bad83f331304d Mon Sep 17 00:00:00 2001
From: Matthias <xmatthias@outlook.com>
Date: Mon, 23 Dec 2019 09:56:12 +0100
Subject: [PATCH] Convert PairlistResolver to static loader

---
 freqtrade/pairlist/pairlistmanager.py    | 14 ++++----
 freqtrade/resolvers/pairlist_resolver.py | 43 ++++++++++++++----------
 tests/pairlist/test_pairlist.py          |  2 +-
 3 files changed, 34 insertions(+), 25 deletions(-)

diff --git a/freqtrade/pairlist/pairlistmanager.py b/freqtrade/pairlist/pairlistmanager.py
index fa5382c37..1530710d2 100644
--- a/freqtrade/pairlist/pairlistmanager.py
+++ b/freqtrade/pairlist/pairlistmanager.py
@@ -28,13 +28,13 @@ class PairListManager():
             if 'method' not in pl:
                 logger.warning(f"No method in {pl}")
                 continue
-            pairl = PairListResolver(pl.get('method'),
-                                     exchange=exchange,
-                                     pairlistmanager=self,
-                                     config=config,
-                                     pairlistconfig=pl,
-                                     pairlist_pos=len(self._pairlists)
-                                     ).pairlist
+            pairl = PairListResolver.load_pairlist(pl.get('method'),
+                                                   exchange=exchange,
+                                                   pairlistmanager=self,
+                                                   config=config,
+                                                   pairlistconfig=pl,
+                                                   pairlist_pos=len(self._pairlists)
+                                                   )
             self._tickers_needed = pairl.needstickers or self._tickers_needed
             self._pairlists.append(pairl)
 
diff --git a/freqtrade/resolvers/pairlist_resolver.py b/freqtrade/resolvers/pairlist_resolver.py
index d849f4ffb..5b5bcee3a 100644
--- a/freqtrade/resolvers/pairlist_resolver.py
+++ b/freqtrade/resolvers/pairlist_resolver.py
@@ -18,23 +18,32 @@ class PairListResolver(IResolver):
     This class contains all the logic to load custom PairList class
     """
 
-    __slots__ = ['pairlist']
+    __slots__ = []
 
-    def __init__(self, pairlist_name: str, exchange, pairlistmanager,
-                 config: dict, pairlistconfig: dict, pairlist_pos: int) -> None:
+    @staticmethod
+    def load_pairlist(pairlist_name: str, exchange, pairlistmanager,
+                      config: dict, pairlistconfig: dict, pairlist_pos: int) -> IPairList:
         """
-        Load the custom class from config parameter
-        :param config: configuration dictionary or None
+        Load the pairlist with pairlist_name
+        :param pairlist_name: Classname of the pairlist
+        :param exchange: Initialized exchange class
+        :param pairlistmanager: Initialized pairlist manager
+        :param config: configuration dictionary
+        :param pairlistconfig: Configuration dedicated to this pairlist
+        :param pairlist_pos: Position of the pairlist in the list of pairlists
+        :return: initialized Pairlist class
         """
-        self.pairlist = self._load_pairlist(pairlist_name, config,
-                                            kwargs={'exchange': exchange,
-                                                    'pairlistmanager': pairlistmanager,
-                                                    'config': config,
-                                                    'pairlistconfig': pairlistconfig,
-                                                    'pairlist_pos': pairlist_pos})
 
-    def _load_pairlist(
-            self, pairlist_name: str, config: dict, kwargs: dict) -> IPairList:
+        return PairListResolver._load_pairlist(pairlist_name, config,
+                                               kwargs={'exchange': exchange,
+                                                       'pairlistmanager': pairlistmanager,
+                                                       'config': config,
+                                                       'pairlistconfig': pairlistconfig,
+                                                       'pairlist_pos': pairlist_pos})
+
+
+    @staticmethod
+    def _load_pairlist(pairlist_name: str, config: dict, kwargs: dict) -> IPairList:
         """
         Search and loads the specified pairlist.
         :param pairlist_name: name of the module to import
@@ -44,11 +53,11 @@ class PairListResolver(IResolver):
         """
         current_path = Path(__file__).parent.parent.joinpath('pairlist').resolve()
 
-        abs_paths = self.build_search_paths(config, current_path=current_path,
-                                            user_subdir=None, extra_dir=None)
+        abs_paths = IResolver.build_search_paths(config, current_path=current_path,
+                                                 user_subdir=None, extra_dir=None)
 
-        pairlist = self._load_object(paths=abs_paths, object_type=IPairList,
-                                     object_name=pairlist_name, kwargs=kwargs)
+        pairlist = IResolver._load_object(paths=abs_paths, object_type=IPairList,
+                                          object_name=pairlist_name, kwargs=kwargs)
         if pairlist:
             return pairlist
         raise OperationalException(
diff --git a/tests/pairlist/test_pairlist.py b/tests/pairlist/test_pairlist.py
index 43285cdb1..e7f098777 100644
--- a/tests/pairlist/test_pairlist.py
+++ b/tests/pairlist/test_pairlist.py
@@ -53,7 +53,7 @@ def test_load_pairlist_noexist(mocker, markets, default_conf):
     with pytest.raises(OperationalException,
                        match=r"Impossible to load Pairlist 'NonexistingPairList'. "
                              r"This class does not exist or contains Python code errors."):
-        PairListResolver('NonexistingPairList', bot.exchange, plm, default_conf, {}, 1)
+        PairListResolver.load_pairlist('NonexistingPairList', bot.exchange, plm, default_conf, {}, 1)
 
 
 def test_refresh_market_pair_not_in_whitelist(mocker, markets, static_pl_conf):