Fix extrusion layer handling in MEOW class by using layer tuples

[FiodarM]

Summary by Sourcery

Bug Fixes:

• Correct extrusion mapping to use the derived or base layer tuple, ensuring extrusions are keyed consistently with GDS layer definitions.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Refactors the MEOW extrusion layer mapping to key extrusions by normalized layer tuples derived from either a layer’s derived_layer or its base layer, ensuring consistent handling of layers in the LayerStack-to-extrusion conversion.

Class diagram for updated MEOW extrusion layer handling

classDiagram
    class MeowEme {
        LayerStack layer_stack
        dict layer_stack_to_extrusion()
        MeowMaterial gf_material_to_meow_material(Material material)
    }

    class LayerStack {
        dict~int,Layer~ layers
    }

    class Layer {
        int layer
        Layer derived_layer
        Material material
    }

    class GdsExtrusionRule {
        MeowMaterial material
    }

    MeowEme --> LayerStack : uses
    LayerStack --> Layer : contains
    MeowEme --> GdsExtrusionRule : creates
    Layer --> Layer : derived_layer

Loading

File-Level Changes

Change	Details	Files
Normalize extrusion mapping keys to use layer tuples derived from either derived_layer or base layer.	Introduce layer_tuple derived via gf.get_layer_tuple from the effective layer (derived_layer if present, otherwise layer.layer) Replace use of layer.layer as the dictionary key with the normalized layer_tuple Adjust creation and appending of extrusion lists to be indexed by layer_tuple instead of layer.layer	gplugins/meow/meow_eme.py

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[sourcery-ai]

Hey - I've found 1 issue, and left some high level feedback:

• The new key construction gf.get_layer_tuple((layer.derived_layer or layer.layer).layer) assumes both derived_layer and layer share a .layer attribute; consider guarding this with clearer typing or intermediate variables so it’s obvious what types are expected and to avoid attribute errors if the structure changes.
• You can simplify the dictionary initialization logic by using extrusions.setdefault(layer_tuple, []).append(...) instead of explicitly checking if layer_tuple not in extrusions.keys().

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The new key construction `gf.get_layer_tuple((layer.derived_layer or layer.layer).layer)` assumes both `derived_layer` and `layer` share a `.layer` attribute; consider guarding this with clearer typing or intermediate variables so it’s obvious what types are expected and to avoid attribute errors if the structure changes.
- You can simplify the dictionary initialization logic by using `extrusions.setdefault(layer_tuple, []).append(...)` instead of explicitly checking `if layer_tuple not in extrusions.keys()`.

## Individual Comments

### Comment 1
<location> `gplugins/meow/meow_eme.py:289` </location>
<code_context>
-            if layer.layer not in extrusions.keys():
-                extrusions[layer.layer] = []
-            extrusions[layer.layer].append(
+            layer_tuple = gf.get_layer_tuple((layer.derived_layer or layer.layer).layer)
+            if layer_tuple not in extrusions.keys():
+                extrusions[layer_tuple] = []
</code_context>

<issue_to_address>
**issue:** Double-check the `.layer` attribute access before `gf.get_layer_tuple`, as it may already accept the layer spec directly.

If `layer.derived_layer` / `layer.layer` is already a valid layer spec for `gf.get_layer_tuple` (int, tuple, or `Layer`-like), chaining `.layer` may be incorrect or overly brittle. Consider passing `layer.derived_layer or layer.layer` directly to `gf.get_layer_tuple`, unless you have a strict guarantee that the extra `.layer` is always valid and non-`None`.
</issue_to_address>

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[joamatab]

Thank you Fiodar!