do not try to catch args if there are only kwargs, added ideas (commented out) for further removing reader selection logic out of ExcelFile class

Author: davidovitch

pandas/io/excel.py

@@ -106,7 +106,7 @@ def open_workbook(self, *args, **kwargs):
         if isinstance(self._open_workbook, type(None)):
             self.load_engine()
         # just in case the user passes an already opened workbook of io_class
-        if isinstance(args[0], self.io_class):
+        if len(args) > 0 and isinstance(args[0], self.io_class):
             return args[0]
         return self._open_workbook(*args, **kwargs)
 
@@ -122,14 +122,21 @@ def is_ext(self, path):
         else:
             return False
 
-    def is_type(self, io):
+    def is_type(self, io):#, engine=None):
         """Verify if the io type is supported by the reader. If the reader is
         not installed, return False.
         """
         if isinstance(io, type(None)):
             return False
         elif isinstance(io, self.io_class):
             return True
+#        elif self.engine == engine:
+#            return True
+#        elif isinstance(io, compat.string_types):
+#            if self.is_ext(io):
+#                return True
+#            else:
+#                return False
         else:
             return False
 
@@ -164,6 +171,24 @@ def _load_engine(self):
             self._open_workbook = xlrd.open_workbook
             self.io_class = xlrd.Book
 
+#    def open_workbook(self, *args, **kwargs):
+#        """Explicitely load the engine again (and trigger an ImportError in the
+#        process) if _open_workbook is set to None.
+#        """
+#        # try to load the engine again and raise import error if required
+#        if isinstance(self._open_workbook, type(None)):
+#            self.load_engine()
+#        io = args[0]
+#        # just in case the user passes an already opened workbook of io_class
+#        if isinstance(io, self.io_class):
+#            return io
+#        # N.B. xlrd.Book has a read attribute too
+#        elif hasattr(io, "read"):
+#            data = io.read()
+#            return self._open_workbook(file_contents=data)
+#
+#        return self._open_workbook(*args, **kwargs)
+
 
 class EZODFFile(BaseFile):
     """File reader class for ODF spreadsheets (depends on ezodf)