Make a generic version of HasChannel

Signed-off-by: liamhuber <[email protected]>

pyiron_workflow/mixin/has_interface_mixins.py

@@ -11,7 +11,7 @@
 from __future__ import annotations
 
 from abc import ABC, abstractmethod
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Generic, TypeVar
 
 if TYPE_CHECKING:
     from pyiron_workflow.channels import Channel
@@ -69,9 +69,7 @@ def full_label(self) -> str:
 
 class HasChannel(ABC):
     """
-    A mix-in class for use with the :class:`Channel` class.
-    A :class:`Channel` is able to (attempt to) connect to any child instance of :class:`HasConnection`
-    by looking at its :attr:`connection` attribute.
+    A mix-in class for use with the :class:`Channel` class and its children.
 
     This is useful for letting channels attempt to connect to non-channel objects
     directly by pointing them to some channel that object holds.
@@ -83,6 +81,16 @@ def channel(self) -> Channel:
         pass
 
 
+ChannelType = TypeVar("ChannelType", bound="Channel")
+
+
+class HasGenericChannel(HasChannel, Generic[ChannelType], ABC):
+    @property
+    @abstractmethod
+    def channel(self) -> ChannelType:
+        pass
+
+
 class HasRun(ABC):
     """
     A mixin to guarantee that the :meth:`run` method exists.

pyiron_workflow/mixin/single_output.py

@@ -7,7 +7,7 @@
 
 from abc import ABC, abstractmethod
 
-from pyiron_workflow.mixin.has_interface_mixins import HasChannel, HasLabel
+from pyiron_workflow.mixin.has_interface_mixins import HasGenericChannel, HasLabel
 from pyiron_workflow.mixin.injection import (
     OutputDataWithInjection,
     OutputsWithInjection,
@@ -18,7 +18,7 @@ class AmbiguousOutputError(ValueError):
     """Raised when searching for exactly one output, but multiple are found."""
 
 
-class ExploitsSingleOutput(HasLabel, HasChannel, ABC):
+class ExploitsSingleOutput(HasLabel, HasGenericChannel[OutputDataWithInjection], ABC):
     @property
     @abstractmethod
     def outputs(self) -> OutputsWithInjection: