better error messages when defining an experiment in interactive envi…

…ronment without a name.

sacred/experiment.py

@@ -53,10 +53,15 @@ def __init__(self, name=None, ingredients=(), interactive=False):
             source-code or reliable reproduction of the runs.
         """
         caller_globals = inspect.stack()[1][0].f_globals
-        if name is None and interactive:
-            raise(RuntimeError('name is required in interactive mode.'))
-        elif name is None:
-            name = os.path.basename(caller_globals['__file__'])
+        if name is None:
+            if interactive:
+                raise RuntimeError('name is required in interactive mode.')
+            mainfile = caller_globals.get('__file__')
+            if mainfile is None:
+                raise RuntimeError('No main-file found. Are you running in '
+                                   'interactive mode? If so please provide a '
+                                   'name and set interactive=True.')
+            name = os.path.basename(mainfile)
             if name.endswith('.py'):
                 name = name[:-3]
             elif name.endswith('.pyc'):

sacred/ingredient.py

@@ -50,7 +50,7 @@ def __init__(self, path, ingredients=(), interactive=False,
         self.commands = OrderedDict()
         # capture some context information
         _caller_globals = _caller_globals or inspect.stack()[1][0].f_globals
-        mainfile_name = _caller_globals.get('__file__')
+        mainfile_name = _caller_globals.get('__file__', '.')
         self.base_dir = os.path.dirname(os.path.abspath(mainfile_name))
         self.doc = _caller_globals.get('__doc__', "")
         self.sources, self.dependencies = \