43 lines
3.7 KiB
Markdown
43 lines
3.7 KiB
Markdown
---
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source_files:
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- Common/DTS.Common.Storage/Classes/Static/CustomChannelFieldSizeAttribute.cs
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generated_at: "2026-04-16T02:11:01.276588+00:00"
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model: "Qwen/Qwen3-Coder-Next-FP8"
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schema_version: 1
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sha256: "96c94c51da2a1b2d"
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---
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# Static
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## 1. Purpose
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This module provides a mechanism to associate custom, non-default field sizes with enum values representing channel fields in the `MMETables.MMEPossibleChannelsFields` enumeration. It enables runtime retrieval of field-specific size metadata via a custom attribute (`CustomChannelFieldSizeAttribute`) and extension methods, supporting scenarios where the default size inference (e.g., based on underlying type or convention) is insufficient or incorrect.
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## 2. Public Interface
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- **`CustomChannelFieldSizeAttribute(int size)`**
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*Constructor.* Creates an attribute instance with the specified field size. `size` must be non-negative (enforced by caller; no validation in constructor).
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- **`int Size { get; }`**
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*Property.* Returns the field size stored in the attribute. Read-only after construction.
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- **`int GetFieldSize(MMETables.MMEPossibleChannelsFields field)`**
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*Extension method.* Retrieves the field size for a given `MMEPossibleChannelsFields` enum value by inspecting its `CustomChannelFieldSizeAttribute`. Throws `NullReferenceException` if the attribute is not applied to the enum value (since `.Size` is accessed on a `null` reference returned by `GetAttribute<>()`).
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- **`TAttribute GetAttribute<TAttribute>(this Enum value)`**
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*Extension method.* Returns the first (and expected only) custom attribute of type `TAttribute` applied to the enum value, or `null` if none exists. Uses reflection to inspect the enum field’s attributes.
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## 3. Invariants
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- `CustomChannelFieldSizeAttribute` is only intended for use on `MMETables.MMEPossibleChannelsFields` enum members.
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- The `Size` property must be set at construction and remains immutable thereafter.
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- `GetFieldSize` assumes exactly one `CustomChannelFieldSizeAttribute` per enum member; behavior is undefined if multiple attributes are applied (though `SingleOrDefault()` would return the first if duplicates exist, which is invalid per attribute semantics).
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- `GetAttribute<TAttribute>` returns `null` if no attribute of type `TAttribute` is present on the enum value.
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## 4. Dependencies
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- **Internal dependencies:**
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- `MMETables.MMEPossibleChannelsFields` enum (from `MMETables` namespace—external to this file but referenced in `GetFieldSize`).
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- Standard .NET reflection APIs (`System.Type`, `System.Reflection.FieldInfo`, `System.Linq.Enumerable`).
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- **No external NuGet or third-party dependencies** beyond the base class library.
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- **Dependent modules:** Any code that needs to retrieve field sizes for `MMEPossibleChannelsFields` values—likely storage or serialization components dealing with channel data.
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## 5. Gotchas
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- **Null reference risk:** `GetFieldSize` will throw `NullReferenceException` if `CustomChannelFieldSizeAttribute` is not applied to the queried enum member (since `GetAttribute<>()` returns `null`, and `.Size` is dereferenced unconditionally). Callers must ensure the attribute is present or guard against `null`.
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- **No validation on `size`:** The constructor accepts any `int`, including negative values. No runtime checks enforce valid size constraints (e.g., `size ≥ 0`).
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- **Reflection overhead:** `GetAttribute<TAttribute>` uses reflection on every call; not suitable for hot paths without caching.
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- **Ambiguity in `MMETables` namespace:** The `MMETables.MMEPossibleChannelsFields` type is referenced but not defined here; its actual definition and available members are unknown from this file alone.
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- **No XML documentation:** The source contains no comments; behavior is inferred solely from code structure. |