Added node composition (#685)

* Added node composition

* Add test for composite configuration.

* fix tests

---------

Co-authored-by: drodarie <d.rodarie@gmail.com>

bsb/config/__init__.py

@@ -33,7 +33,7 @@
     ConfigurationAttribute,
 )
 from .._util import ichain
-from ._make import walk_node_attributes, walk_nodes
+from ._make import walk_node_attributes, walk_nodes, compose_nodes
 from ._hooks import on, before, after, run_hook, has_hook
 from .. import plugins
 from ..exceptions import ConfigTemplateNotFoundError, ParserError, PluginError
@@ -68,6 +68,7 @@ def __init__(self, name):
 
     walk_node_attributes = staticmethod(walk_node_attributes)
     walk_nodes = staticmethod(walk_nodes)
+    compose_nodes = staticmethod(compose_nodes)
     on = staticmethod(on)
     after = staticmethod(after)
     before = staticmethod(before)

bsb/config/_make.py

@@ -99,6 +99,16 @@ def __new__(cls, *args, **kwargs):
     return NodeMeta
 
 
+def compose_nodes(*node_classes):
+    """
+    Create a composite mixin class of the given classes. Inherit from the returned class
+    to inherit from more than one node class.
+
+    """
+    meta = type("ComposedMetaclass", tuple(type(cls) for cls in node_classes), {})
+    return meta("CompositionMixin", node_classes, {})
+
+
 def compile_class(cls):
     cls_dict = dict(cls.__dict__)
     if "__dict__" in cls_dict:

docs/config/nodes.rst

@@ -200,6 +200,43 @@ that fast so caching them is recommended). The returned plugin objects should be
 configuration node classes. These classes will then be used to further handle the given
 configuration.
 
+Node inheritance
+================
+
+Classes decorated with node decorators have their class and metaclass machinery rewritten.
+Basic inheritance works like this:
+
+.. code-block:: python
+
+    @config.node
+    class NodeA:
+        pass
+
+    @config.node
+    class NodeB(NodeA):
+        pass
+
+However, when inheriting from more than one node class you will run into a metaclass
+conflict. To solve it, use :func:`.config.compose_nodes`:
+
+.. code-block:: python
+
+    from bsb import config
+    from bsb.config import compose_nodes
+
+    @config.node
+    class NodeA:
+        pass
+
+    @config.node
+    class NodeB:
+        pass
+
+    @config.node
+    class NodeC(compose_nodes(NodeA, NodeB)):
+        pass
+
+
 .. _config_attrs:
 
 Configuration attributes

requirements.txt

@@ -29,4 +29,4 @@ NEURON==8.2.2
 nrn-subprocess==1.3.4
 
 # Plugins
-bsb-hdf5==0.7.1
+bsb-hdf5==0.7.2

setup.py

@@ -17,7 +17,7 @@
     long_description = fh.read()
 
 requires = [
-    "bsb-hdf5~=0.7.1",
+    "bsb-hdf5~=0.7.2",
     "h5py~=3.0",
     "numpy~=1.19",
     "scipy~=1.5",

tests/test_configuration.py

@@ -4,7 +4,7 @@
 import json
 from bsb.core import Scaffold
 from bsb import config
-from bsb.config import from_json, Configuration, _attrs
+from bsb.config import from_json, Configuration, _attrs, compose_nodes
 from bsb.config import types
 from bsb.exceptions import (
     CfgReferenceError,
@@ -1256,3 +1256,28 @@ def test_booted_root(self):
         self.assertIsNone(_attrs._booted_root(cfg.partitions), "shouldnt be booted yet")
         Scaffold(cfg)
         self.assertIsNotNone(_attrs._booted_root(cfg), "now it should be booted")
+
+
+class TestNodeComposition(unittest.TestCase):
+    def setUp(self):
+        @config.node
+        class NodeA:
+            attrA = config.attr()
+
+        @config.node
+        class NodeB:
+            attrB = config.attr()
+
+        @config.node
+        class NodeC(compose_nodes(NodeA, NodeB)):
+            attrC = config.attr()
+
+        self.tested = NodeC()
+
+    def test_composite_node(self):
+        assert hasattr(self.tested, "attrA")
+        assert type(self.tested.attrA == config.ConfigurationAttribute)
+        assert hasattr(self.tested, "attrB")
+        assert type(self.tested.attrB == config.ConfigurationAttribute)
+        assert hasattr(self.tested, "attrC")
+        assert type(self.tested.attrC == config.ConfigurationAttribute)