Simplify implementation of on-disk resources (#35)

I had factored out the repetitive pattern that connected
on-disk and in-memory implementations, but mypy was very
difficult to please. Now I have removed the decorator
and allowed the repetition.
This makes it easier to read and maintain so meh

src/abcdmicro/io.py

@@ -1,12 +1,13 @@
 from __future__ import annotations
 
-from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Any, Callable, TypeVar, get_type_hints
+from typing import Any
 
 import itk
+import numpy as np
 from dipy.io.gradients import read_bvals_bvecs
+from numpy.typing import NDArray
 
 from abcdmicro.resource import (
     BvalResource,
@@ -17,54 +18,9 @@
     VolumeResource,
 )
 
-T = TypeVar("T", bound="LoadableResource")
 
-
-class LoadableResource(ABC):
-    """Base class for on-disk resources that have a load method that converts them into in-memory resources"""
-
-    @abstractmethod
-    def load(self) -> Any:
-        """Load this resource to get an in-memory version of it."""
-
-
-def implement_via_loading(method_names: list[str]) -> Callable[[type[T]], type[T]]:
-    """Decorator that implements the listed abstract methods of a LoadableResource class by calling the
-    load() method and then using the loaded object's method of the same name."""
-
-    def implement_via_loading_decorator(cls: type[T]) -> type[T]:
-        for method_name in method_names:
-
-            def method(self, method_name=method_name):  # type: ignore[no-untyped-def]
-                return getattr(self.load(), method_name)()
-
-            method.__name__ = method_name
-            method.__doc__ = f"Automatically implemented method that returns `self.load().{method_name}()`."
-
-            for parent_class in cls.__bases__:
-                if hasattr(parent_class, method_name):
-                    parent_method = getattr(parent_class, method_name)
-                    return_type = get_type_hints(parent_method).get("return", Any)
-                    method.__annotations__ = {"return": return_type}
-                    break
-
-            setattr(cls, method_name, method)
-
-        # If the automatically implemented methods were abstract methods, then remove them from the set
-        # to indicate that they have been implemented.
-        if hasattr(cls, "__abstractmethods__"):
-            cls.__abstractmethods__ = frozenset(
-                name for name in cls.__abstractmethods__ if name not in method_names
-            )
-
-        return cls
-
-    return implement_via_loading_decorator
-
-
-@implement_via_loading(["get_array", "get_metadata"])
 @dataclass
-class NiftiVolumeResrouce(VolumeResource):  # type: ignore[type-var]
+class NiftiVolumeResrouce(VolumeResource):
     """A volume or volume stack that is saved to disk in the nifti file format."""
 
     path: Path
@@ -73,10 +29,15 @@ class NiftiVolumeResrouce(VolumeResource):  # type: ignore[type-var]
     def load(self) -> InMemoryVolumeResource:
         return InMemoryVolumeResource(itk.imread(self.path))
 
+    def get_array(self) -> NDArray[Any]:
+        return self.load().get_array()
+
+    def get_metadata(self) -> dict[Any, Any]:
+        return self.load().get_metadata()
+
 
-@implement_via_loading(["get"])
 @dataclass
-class FslBvalResource(BvalResource, LoadableResource):
+class FslBvalResource(BvalResource):
     """A b-value list that is saved to disk in the FSL text file format."""
 
     path: Path
@@ -86,10 +47,12 @@ def load(self) -> InMemoryBvalResource:
         bvals_array, _ = read_bvals_bvecs(self.path, None)
         return InMemoryBvalResource(bvals_array)
 
+    def get(self) -> NDArray[np.floating]:
+        return self.load().get()
+
 
-@implement_via_loading(["get"])
 @dataclass
-class FslBvecResource(BvecResource, LoadableResource):
+class FslBvecResource(BvecResource):
     """A b-vector list that is saved to disk in the FSL text file format."""
 
     path: Path
@@ -98,3 +61,6 @@ class FslBvecResource(BvecResource, LoadableResource):
     def load(self) -> InMemoryBvecResource:
         _, bvecs_array = read_bvals_bvecs(None, self.path)
         return InMemoryBvecResource(bvecs_array)
+
+    def get(self) -> NDArray[np.floating]:
+        return self.load().get()

tests/test_io.py

@@ -51,5 +51,5 @@ def test_nifti_volume_resource(volume_array):
                 ]
             ),
         )
-        volume_resource = NiftiVolumeResrouce(path=volume_file)  # type: ignore[abstract]
+        volume_resource = NiftiVolumeResrouce(path=volume_file)
         assert np.allclose(volume_resource.get_array(), volume_array)