58 lines
3.9 KiB
Markdown
58 lines
3.9 KiB
Markdown
---
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source_files:
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- Common/DTS.Common/Events/ISO/ExtraPropertiesChangedEvent.cs
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generated_at: "2026-04-16T03:25:01.894095+00:00"
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model: "Qwen/Qwen3-Coder-Next-FP8"
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schema_version: 1
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sha256: "61eef1209c66c784"
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---
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# ISO
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### 1. Purpose
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This module defines event infrastructure for propagating changes to *extra properties* within the ISO domain layer of the DTS system. Specifically, it provides a Prism-based pub/sub event (`ExtraPropertiesChangedEvent`) and its associated argument container (`ExtraPropertiesChangedEventArgs`) to decouple producers and consumers of property updates—enabling reactive UI or business logic components to respond when a collection of `IExtraProperty` instances is modified, while preserving provenance via `Producer` and `Consumer` references.
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---
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### 2. Public Interface
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- **`ExtraPropertiesChangedEvent`**
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- *Type:* `class` inheriting from `PubSubEvent<ExtraPropertiesChangedEventArgs>`
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- *Behavior:* A Prism `PubSubEvent` used to publish and subscribe to notifications about changes to extra properties. Subscribers receive an `ExtraPropertiesChangedEventArgs` payload.
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- **`ExtraPropertiesChangedEventArgs`**
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- *Type:* `class`
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- *Constructor:* `ExtraPropertiesChangedEventArgs(IList<IExtraProperty> extraProperties, object producer, object consumer)`
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- *Properties:*
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- `IList<IExtraProperty> ExtraProperties { get; }` — The updated collection of extra properties.
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- `object Producer { get; }` — The object instance that initiated or caused the change.
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- `object Consumer { get; }` — The object instance that is the intended recipient or target of the change.
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- *Behavior:* Encapsulates the data for an `ExtraPropertiesChangedEvent` payload. All properties are read-only after construction.
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---
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### 3. Invariants
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- `ExtraProperties` is non-null (enforced by constructor assignment; no null-check is present, so passing `null` will result in a `NullReferenceException` at runtime).
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- `Producer` and `Consumer` may be `null` (no validation is enforced in the constructor).
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- The `ExtraProperties` list reference is immutable in terms of property exposure (only a getter), but the *contents* of the list are not defensively copied—consumers must treat the list as potentially mutable if the producer retains a reference.
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- The event is strictly *publish-once-per-change*; no batching or deduplication semantics are implied.
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---
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### 4. Dependencies
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- **Dependencies *on* this module:**
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- `DTS.Common.Interface.ISO.ExtraProperties` — Provides the `IExtraProperty` interface used in `ExtraPropertiesChangedEventArgs.ExtraProperties`.
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- `Prism.Events` — Provides the `PubSubEvent<T>` base class.
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- `System.Collections.Generic` — Provides `IList<T>`.
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- **Dependencies *of* this module:**
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- This module is consumed by components that use Prism event aggregation (e.g., view models, services) to react to extra property changes in the ISO domain.
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- No other modules in this file depend on it—this is a leaf event definition.
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---
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### 5. Gotchas
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- **No defensive copying:** The `ExtraProperties` list is assigned directly from the constructor argument; if the caller mutates the list *after* constructing the args object, subscribers may observe unexpected changes.
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- **No validation on `Producer`/`Consumer`:** These may be `null`, and subscribers must handle this case explicitly.
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- **No versioning or metadata:** The event carries no timestamp, correlation ID, or change type (e.g., add/remove/replace), limiting traceability or differential processing.
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- **Assumes Prism event aggregator usage:** The class is tightly coupled to Prism’s `PubSubEvent<T>`—not usable in isolation without Prism infrastructure.
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- **No documentation on semantics of `Producer` vs `Consumer`:** The distinction between the two is not clarified in the source—consumers must infer intent (e.g., `Producer` = source of change, `Consumer` = target component). |