document the use of entry_points to register new backends

docs/source/developer.rst

@@ -66,7 +66,27 @@ We may eventually refactor ``AbstractFileSystem`` to split the default implement
 the set of methods that you might implement in a new backend, and the
 documented end-user API.
 
-For now, new backends must register themselves on import
+In order to register a new backend with fsspec, new backends should register
+themselves using the `entry_points <https://setuptools.readthedocs.io/en/latest/userguide/quickstart.html#entry-points-and-automatic-script-creation>`_
+facility from setuptools. In particular, if you want to register a new
+filesystem protocol ``myfs`` which is provided by the ``MyFS`` class in
+the ``myfs`` package, add the following to your ``setup.py``:
+
+.. code-block:: python
+
+    setuptools.setup(
+        ...
+        entry_points={
+            'fsspec.specs': [
+                'myfs=myfs.MyFS',
+            ],
+        },
+        ...
+    )
+
+
+Alternatively, the previous method of registering a new backend can be used.
+That is, new backends must register themselves on import
 (``register_implementation``) or post a PR to the ``fsspec`` repo
 asking to be included in ``fsspec.registry.known_implementations``.
 

fsspec/__init__.py

@@ -42,4 +42,4 @@
     entry_points = entry_points()
     for spec in entry_points.get("fsspec.specs", []):
         err_msg = f"Unable to load filesystem from {spec}"
-        register_implementation(spec.name, spec.module, errtxt=err_msg)
+        register_implementation(spec.name, spec.value.replace(":", "."), errtxt=err_msg)