Fixes as suggested in the comments for pull request #1238

Author: Ludvig Kihlman

nbgrader/apps/api.py

@@ -59,6 +59,9 @@ def __init__(self, coursedir=None, authenticator=None, exchange=None, **kwargs):
         authenticator : :class:~`nbgrader.auth.BaseAuthenticator`
             (Optional) An authenticator instance for communicating with an
             external database.
+        exchange : :class:~`nbgrader.exchange.ExchangeFactory`
+            (Optional) A factory for creating the exchange classes used
+            for distributing assignments and feedback.
         kwargs:
             Additional keyword arguments (e.g. ``parent``, ``config``)
 

nbgrader/apps/dbapp.py

@@ -12,7 +12,6 @@
 
 from . import NbGrader
 from ..api import Gradebook, MissingEntry, Student, Assignment
-from ..exchange import ExchangeList
 from .. import dbutil
 
 aliases = {

nbgrader/docs/source/exchange/exchange_api.rst

@@ -306,7 +306,7 @@ When writing your own Exchange
 - nbgrader functionality requires a file called ``timestamp.txt`` to be in the submission, containing the timestamp of that submission. The creation of this file is the responsibility of this class.
 - Whilst nothing is done *as yet*, the default exchange checks the names of submitted notebooks, and logs differences.
 - Submissions need to record ``student_id``, as well as ``course_id`` & ``assignment_id``
-- The default exchange copies files to both an ``inbound`` and ``cache`` store. This may be significant considering ``ExchangeList``
+- The default exchange copies files to both an ``inbound`` and ``cache`` store.
 
 ExchangeList Date Return structure
 ----------------------------------

nbgrader/docs/source/exchange/exchange_plugin.rst

@@ -21,7 +21,7 @@ The exchange package is organised as follows::
     │   └── submit.py
     └── exchange_factory.py
 
-The ``exchange.abc`` package contain all the Abstract Base Classes that custom exchange packages need to implement.
+The ``exchange.abc`` package contains all the Abstract Base Classes that custom exchange packages need to implement.
 The ``exchange.default`` package is a default filesystem based implementation. The exchange_factory.py file contains
 the defintion for the ExchangeFactory class that is used to create instances of the exchange classes.
 

nbgrader/exchange/abc/__init__.py

@@ -21,4 +21,4 @@
     "ExchangeReleaseAssignment",
     "ExchangeReleaseFeedback",
     "ExchangeSubmit"
-]
+]

nbgrader/exchange/abc/collect.py

@@ -14,13 +14,3 @@ class ExchangeCollect(Exchange):
         default_value=True,
         help="Whether to cross-check the student_id with the UNIX-owner of the submitted directory."
     ).tag(config=True)
-
-
-    def init_src(self):
-        pass
-
-    def init_dest(self):
-        pass
-
-    def copy_files(self):
-        pass

nbgrader/exchange/abc/exchange.py

@@ -1,16 +1,12 @@
-import os
 import datetime
-import sys
 
 from textwrap import dedent
 
 from dateutil.tz import gettz
 from dateutil.parser import parse
 from traitlets.config import LoggingConfigurable
-from traitlets import Unicode, Bool, Instance, Type, default, validate, TraitError
-from jupyter_core.paths import jupyter_data_dir
+from traitlets import Unicode, Instance, validate, TraitError
 
-from nbgrader.utils import check_directory, ignore_patterns, self_owned
 from nbgrader.coursedir import CourseDirectory
 from nbgrader.auth import Authenticator
 

nbgrader/exchange/abc/fetch_assignment.py

@@ -1,16 +1,8 @@
-import os
-import shutil
-
 from traitlets import Bool
 
 from .exchange import Exchange
-from nbgrader.utils import check_mode
 
 
 class ExchangeFetchAssignment(Exchange):
 
     replace_missing_files = Bool(False, help="Whether to replace missing files on fetch").tag(config=True)
-
-    def copy_if_missing(self, src, dest, ignore=None):
-        pass
-

nbgrader/exchange/abc/list.py

@@ -1,36 +1,28 @@
-
-import hashlib
-
 from traitlets import Bool
 from .exchange import Exchange
 
 
-def _checksum(path):
-    m = hashlib.md5()
-    m.update(open(path, 'rb').read())
-    return m.hexdigest()
-
-
 class ExchangeList(Exchange):
 
     inbound = Bool(False, help="List inbound files rather than outbound.").tag(config=True)
     cached = Bool(False, help="List assignments in submission cache.").tag(config=True)
     remove = Bool(False, help="Remove, rather than list files.").tag(config=True)
 
-    def parse_assignment(self, assignment):
-        pass
-
-    def format_inbound_assignment(self, info):
-        pass
+    def list_files(self):
+        """Return list of available files """
+        raise NotImplementedError
 
-    def format_outbound_assignment(self, info):
-        pass
+    def remove_files(self):
+        """Remove available files """
+        raise NotImplementedError
 
-    def parse_assignments(self):
-        pass
+    def start(self):
+        if self.inbound and self.cached:
+            self.fail("Options --inbound and --cached are incompatible.")
 
-    def list_files(self):
-        pass
+        super(ExchangeList, self).start()
 
-    def remove_files(self):
-        pass
+        if self.remove:
+            return self.remove_files()
+        else:
+            return self.list_files()

nbgrader/exchange/abc/release_feedback.py

@@ -2,4 +2,4 @@
 
 
 class ExchangeReleaseFeedback(Exchange):
-    pass
+    pass