support exponential euler integration (#25)

* fix

* support `exponential euler` integration

* update

dendritex/__init__.py

@@ -23,9 +23,18 @@
 from ._base import __all__ as _base_all
 from ._integrators import *
 from ._integrators import __all__ as _integrators_all
+from ._protocol import *
+from ._protocol import __all__ as _protocol_all
 
 __all__ = (
-    ['neurons', 'ions', 'channels'] +
-    _base_all +
-    _integrators_all
+    ['neurons', 'ions', 'channels']
+    + _base_all
+    + _integrators_all
+    + _protocol_all
+)
+
+del (
+    _base_all,
+    _integrators_all,
+    _protocol_all,
 )

dendritex/_base.py

@@ -24,7 +24,7 @@
 import numpy as np
 from brainstate.mixin import _JointGenericAlias
 
-from ._integrators import DiffEqModule
+from ._protocol import DiffEqModule
 from ._misc import set_module_as, Container, TreeNode
 
 __all__ = [
@@ -101,7 +101,7 @@ def post_integral(self, *args, **kwargs):
         """
         For the neuron model, the `post_integral()` is the `update()` function.
         """
-        return self.update(*args, **kwargs)
+        pass
 
     def init_state(self, batch_size=None):
         nodes = self.nodes(IonChannel, allowed_hierarchy=(1, 1)).values()
@@ -193,6 +193,13 @@ def init_state(self, *args, **kwargs):
 
 
 class IonInfo(NamedTuple):
+    """
+    The information of the ion.
+
+    Attributes:
+        E: The reversal potential.
+        C: The ion concentration.
+    """
     C: bst.typing.ArrayLike
     E: bst.typing.ArrayLike
 
@@ -211,12 +218,6 @@ class Ion(IonChannel, Container):
     # The type of the master object.
     root_type = HHTypedNeuron
 
-    # Reversal potential.
-    E: bst.typing.ArrayLike | bst.State
-
-    # Ion concentration.
-    C: bst.typing.ArrayLike | bst.State
-
     def __init__(
         self,
         size: bst.typing.Size,
@@ -290,7 +291,7 @@ def register_external_current(self, key: str, fun: Callable):
             raise ValueError
         self._external_currents[key] = fun
 
-    def pack_info(self):
+    def pack_info(self) -> IonInfo:
         E = self.E
         E = E.value if isinstance(E, bst.State) else E
         C = self.C.value if isinstance(self.C, bst.State) else self.C