owdataset: Do not capture self in closure

Parameterize and move the functions out of the class.

Orange/widgets/data/owdatasets.py

@@ -44,6 +44,15 @@ def ensure_local(index_url, file_path, local_cache_path,
     return localfiles.localpath_download(*file_path, callback=progress_advance)
 
 
+def list_remote(server: str) -> Dict[Tuple[str, ...], dict]:
+    client = ServerFiles(server)
+    return client.allinfo()
+
+
+def list_local(path: str) -> Dict[Tuple[str, ...], dict]:
+    return LocalFiles(path).allinfo()
+
+
 def format_exception(error):
     # type: (BaseException) -> str
     return "\n".join(traceback.format_exception_only(type(error), error))
@@ -256,7 +265,7 @@ def __init__(self):
         self.setStatusMessage("Initializing")
 
         self._executor = ThreadPoolExecutor(max_workers=1)
-        f = self._executor.submit(self.list_remote)
+        f = self._executor.submit(list_remote, self.INDEX_URL)
         w = FutureWatcher(f, parent=self)
         w.done.connect(self.__set_index)
 
@@ -349,7 +358,7 @@ def __set_index(self, f):
         assert f.done()
         self.setBlocking(False)
         self.setStatusMessage("")
-        self.allinfo_local = self.list_local()
+        self.allinfo_local = list_local(self.local_cache_path)
 
         try:
             self.allinfo_remote = f.result()
@@ -385,7 +394,7 @@ def __set_index(self, f):
 
     def __update_cached_state(self):
         model = self.view.model().sourceModel()
-        localinfo = self.list_local()
+        localinfo = list_local(self.local_cache_path)
         assert isinstance(model, QStandardItemModel)
         allinfo = []
         for i in range(model.rowCount()):
@@ -552,15 +561,6 @@ def load_and_output(self, path):
     def load_data(path):
         return Orange.data.Table(path)
 
-    def list_remote(self):
-        # type: () -> Dict[Tuple[str, ...], dict]
-        client = ServerFiles(server=self.INDEX_URL)
-        return client.allinfo()
-
-    def list_local(self):
-        # type: () -> Dict[Tuple[str, ...], dict]
-        return LocalFiles(self.local_cache_path).allinfo()
-
 
 class FutureWatcher(QObject):
     done = Signal(object)