Look at the full collection of Exchange classes

nbgrader/apps/baseapp.py

@@ -149,35 +149,25 @@ def all_configurable_classes(self) -> TypingList[MetaHasTraits]:
             if len(app.class_traits(config=True)) > 0:
                 classes.append(app)
 
+        def _collect_configurables(module):
+            """Return a list of all configurable classes from a module"""
+
+            for name in module.__all__:
+                cls = getattr(module, name)
+                if hasattr(cls, "class_traits") and cls.class_traits(config=True):
+                    classes.append(cls)
+
         # include plugins that have configurable options
-        for pg_name in plugins.__all__:
-            pg = getattr(plugins, pg_name)
-            if pg.class_traits(config=True):
-                classes.append(pg)
+        _collect_configurables(plugins)
 
         # include all preprocessors that have configurable options
-        for pp_name in preprocessors.__all__:
-            pp = getattr(preprocessors, pp_name)
-            if len(pp.class_traits(config=True)) > 0:
-                classes.append(pp)
-
-        # include all the exchange actions
-        for ex_name in exchange.__all__:
-            ex = getattr(exchange, ex_name)
-            if hasattr(ex, "class_traits") and ex.class_traits(config=True):
-                classes.append(ex)
+        _collect_configurables(preprocessors)
 
         # include all the default exchange actions
-        for ex_name in exchange.default.__all__:
-            ex = getattr(exchange, ex_name)
-            if hasattr(ex, "class_traits") and ex.class_traits(config=True):
-                classes.append(ex)
+        _collect_configurables(exchange.default)
 
         # include all the converters
-        for ex_name in converters.__all__:
-            ex = getattr(converters, ex_name)
-            if hasattr(ex, "class_traits") and ex.class_traits(config=True):
-                classes.append(ex)
+        _collect_configurables(converters)
 
         return classes
 

nbgrader/apps/collectapp.py

@@ -3,7 +3,8 @@
 from traitlets import default
 
 from .baseapp import NbGrader, nbgrader_aliases, nbgrader_flags
-from ..exchange import Exchange, ExchangeCollect, ExchangeError
+from ..exchange.default import Exchange, ExchangeCollect
+from ..exchange import ExchangeError
 
 
 aliases = {}

nbgrader/exchange/__init__.py

@@ -1,21 +1,28 @@
-
-from nbgrader.exchange.abc import (Exchange, ExchangeError, ExchangeCollect, ExchangeFetch, ExchangeFetchAssignment,
-                                   ExchangeFetchFeedback, ExchangeList, ExchangeReleaseAssignment, ExchangeRelease,
-                                   ExchangeReleaseFeedback, ExchangeSubmit, ExchangeReleaseFeedback)
+import warnings
+from nbgrader.exchange.abc import  ExchangeError
+from nbgrader.exchange import abc, default
 from .exchange_factory import ExchangeFactory
 
+def __getattr__(name):
+    if name in abc.__all__:
+        warnings.warn(
+            f"Importing {name} from nbgrader.exchange is deprecated."
+            " Import from nbgrader.exchange.abc or the specific "
+            " exchange implementation instead.".format(name),
+            DeprecationWarning,
+            stacklevel=2
+        )
+
+    if hasattr(abc, name):
+        return getattr(abc, name)
+    elif hasattr(default, name):
+        return getattr(default, name)
+
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
+
 __all__ = [
-    "Exchange",
-    "ExchangeError",
-    "ExchangeCollect",
-    "ExchangeFetch",
-    "ExchangeFetchAssignment",
-    "ExchangeFetchFeedback",
-    "ExchangeList",
-    "ExchangeRelease",
-    "ExchangeReleaseAssignment",
-    "ExchangeReleaseFeedback",
-    "ExchangeSubmit",
+    "abc",
+    "default",
     "ExchangeFactory",
-    "default"
+    "ExchangeError",
 ]

nbgrader/exchange/abc/__init__.py

@@ -1,13 +1,13 @@
-from .exchange import ExchangeError, Exchange
-from .submit import ExchangeSubmit
-from .release_feedback import ExchangeReleaseFeedback
-from .release import ExchangeRelease
-from .release_assignment import ExchangeReleaseAssignment
-from .fetch_feedback import ExchangeFetchFeedback
-from .fetch import ExchangeFetch
-from .fetch_assignment import ExchangeFetchAssignment
-from .collect import ExchangeCollect
-from .list import ExchangeList
+from .exchange import ExchangeError, ABCExchange as Exchange
+from .submit import ABCExchangeSubmit as ExchangeSubmit
+from .release_feedback import ABCExchangeReleaseFeedback as ExchangeReleaseFeedback
+from .release import ABCExchangeRelease as ExchangeRelease
+from .release_assignment import ABCExchangeReleaseAssignment as ExchangeReleaseAssignment
+from .fetch_feedback import ABCExchangeFetchFeedback as ExchangeFetchFeedback
+from .fetch import ABCExchangeFetch as ExchangeFetch
+from .fetch_assignment import ABCExchangeFetchAssignment as ExchangeFetchAssignment
+from .collect import ABCExchangeCollect as ExchangeCollect
+from .list import ABCExchangeList as ExchangeList
 
 __all__ = [
     "Exchange",

nbgrader/exchange/abc/collect.py

@@ -1,9 +1,9 @@
 from traitlets import Bool
 
-from .exchange import Exchange
+from .exchange import ABCExchange
 
 
-class ExchangeCollect(Exchange):
+class ABCExchangeCollect(ABCExchange):
 
     update = Bool(
         False,

nbgrader/exchange/abc/exchange.py

@@ -1,4 +1,5 @@
 import datetime
+from abc import abstractmethod
 
 from textwrap import dedent
 
@@ -15,7 +16,11 @@ class ExchangeError(Exception):
     pass
 
 
-class Exchange(LoggingConfigurable):
+class ABCExchange(LoggingConfigurable):
+    """
+    The abstract Exchange, which underlies every step in the exchange process.
+    """
+
     assignment_dir = Unicode(
         ".",
         help=dedent(
@@ -51,7 +56,7 @@ def _valid_timestamp_format(self, proposal):
     def __init__(self, coursedir=None, authenticator=None, **kwargs):
         self.coursedir = coursedir
         self.authenticator = authenticator
-        super(Exchange, self).__init__(**kwargs)
+        super(ABCExchange, self).__init__(**kwargs)
 
     def fail(self, msg):
         self.log.fatal(msg)
@@ -64,17 +69,17 @@ def set_timestamp(self):
             self.fail("Invalid timezone: {}".format(self.timezone))
         self.timestamp = datetime.datetime.now(tz).strftime(self.timestamp_format)
 
+    @abstractmethod
     def init_src(self):
         """Compute and check the source paths for the transfer."""
-        raise NotImplementedError
 
+    @abstractmethod
     def init_dest(self):
         """Compute and check the destination paths for the transfer."""
-        raise NotImplementedError
 
+    @abstractmethod
     def copy_files(self):
         """Actually do the file transfer."""
-        raise NotImplementedError
 
     def start(self):
         self.set_timestamp()

nbgrader/exchange/abc/fetch.py

@@ -1,15 +1,15 @@
 import warnings
 
-from .fetch_assignment import ExchangeFetchAssignment
+from .fetch_assignment import ABCExchangeFetchAssignment
 
 
-class ExchangeFetch(ExchangeFetchAssignment):
+class ABCExchangeFetch(ABCExchangeFetchAssignment):
 
     def __init__(self, *args, **kwargs):
-        super(ExchangeFetch, self).__init__(*args, **kwargs)
+        super(ABCExchangeFetch, self).__init__(*args, **kwargs)
         msg = (
-            "The ExchangeFetch class is now deprecated, please use "
-            "ExchangeFetchAssignment instead. This class will be removed in a "
+            "The ABCExchangeFetch class is now deprecated, please use "
+            "ABCExchangeFetchAssignment instead. This class will be removed in a "
             "future version of nbgrader.")
         warnings.warn(msg, DeprecationWarning)
         self.log.warning(msg)

nbgrader/exchange/abc/fetch_assignment.py

@@ -1,8 +1,8 @@
 from traitlets import Bool
 
-from .exchange import Exchange
+from .exchange import ABCExchange
 
 
-class ExchangeFetchAssignment(Exchange):
+class ABCExchangeFetchAssignment(ABCExchange):
 
     replace_missing_files = Bool(False, help="Whether to replace missing files on fetch").tag(config=True)

nbgrader/exchange/abc/fetch_feedback.py

@@ -1,5 +1,5 @@
-from .exchange import Exchange
+from .exchange import ABCExchange
 
 
-class ExchangeFetchFeedback(Exchange):
+class ABCExchangeFetchFeedback(ABCExchange):
     pass

nbgrader/exchange/abc/list.py

@@ -1,8 +1,8 @@
 from traitlets import Bool
-from .exchange import Exchange
+from .exchange import ABCExchange
 
 
-class ExchangeList(Exchange):
+class ABCExchangeList(ABCExchange):
 
     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)
@@ -20,7 +20,7 @@ def start(self):
         if self.inbound and self.cached:
             self.fail("Options --inbound and --cached are incompatible.")
 
-        super(ExchangeList, self).start()
+        super(ABCExchangeList, self).start()
 
         if self.remove:
             return self.remove_files()

nbgrader/exchange/abc/release.py

@@ -1,15 +1,15 @@
 import warnings
 
-from .release_assignment import ExchangeReleaseAssignment
+from .release_assignment import ABCExchangeReleaseAssignment
 
 
-class ExchangeRelease(ExchangeReleaseAssignment):
+class ABCExchangeRelease(ABCExchangeReleaseAssignment):
 
     def __init__(self, *args, **kwargs):
-        super(ExchangeRelease, self).__init__(*args, **kwargs)
+        super(ABCExchangeRelease, self).__init__(*args, **kwargs)
         msg = (
-            "The ExchangeRelease class is now deprecated, please use "
-            "ExchangeReleaseAssignment instead. This class will be removed in "
+            "The ABCExchangeRelease class is now deprecated, please use "
+            "ABCExchangeReleaseAssignment instead. This class will be removed in "
             "a future version of nbgrader.")
         warnings.warn(msg, DeprecationWarning)
         self.log.warning(msg)

nbgrader/exchange/abc/release_assignment.py

@@ -1,8 +1,8 @@
 from traitlets import Bool
 
-from .exchange import Exchange
+from .exchange import ABCExchange
 
 
-class ExchangeReleaseAssignment(Exchange):
+class ABCExchangeReleaseAssignment(ABCExchange):
 
     force = Bool(False, help="Force overwrite existing files in the exchange.").tag(config=True)

nbgrader/exchange/abc/release_feedback.py

@@ -1,5 +1,5 @@
-from .exchange import Exchange
+from .exchange import ABCExchange
 
 
-class ExchangeReleaseFeedback(Exchange):
+class ABCExchangeReleaseFeedback(ABCExchange):
     pass

nbgrader/exchange/abc/submit.py

@@ -1,10 +1,10 @@
 from textwrap import dedent
 from traitlets import Bool
 
-from .exchange import Exchange
+from .exchange import ABCExchange
 
 
-class ExchangeSubmit(Exchange):
+class ABCExchangeSubmit(ABCExchange):
 
     strict = Bool(
         False,

nbgrader/exchange/default/exchange.py

@@ -17,6 +17,10 @@
 
 
 class Exchange(ABCExchange):
+    """
+    The default implementation of an Exchange based on the local file system.
+    """
+
     root = Unicode(
         "/usr/local/share/nbgrader/exchange",
         help="The nbgrader exchange directory writable to everyone. MUST be preexisting."