DP44/enriched-qwen3-coder-next/Common/DTS.Common/Events/GroupTemplates/TemplateChannelList.md

source_files, generated_at, model, schema_version, sha256

source_files	generated_at	model	schema_version	sha256
Common/DTS.Common/Events/GroupTemplates/TemplateChannelList/TemplateChannelListOrderChangedEvent.cs Common/DTS.Common/Events/GroupTemplates/TemplateChannelList/TemplateChannelListSelectionChangedEvent.cs Common/DTS.Common/Events/GroupTemplates/TemplateChannelList/TemplateChannelListRequiredChangedEvent.cs	2026-04-16T03:26:02.944009+00:00	Qwen/Qwen3-Coder-Next-FP8	1	0971a3dcff5effca

TemplateChannelList

Documentation: TemplateChannelList Events Module

1. Purpose

This module defines Prism-based pub/sub events used to signal changes in the state of a template channel list—a UI or business construct representing ordered, configurable channels associated with a group template. Specifically, it enables decoupled communication between components that manage or consume channel lists (e.g., UI views, view models, or services), notifying them when the order, selection, or required-ness of channels changes. Though the XML documentation comments are misleading (referring to “template selection” instead of channel list state), the actual event types and payloads indicate they are concerned with channel-level state transitions.

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2. Public Interface

TemplateChannelListOrderChangedEvent

• Type: class
• Inherits: PubSubEvent<IGroupTemplateChannel>
• Behavior: Published when the ordering of channels in a template channel list changes. The payload is the single channel whose position has changed (e.g., moved up/down in the list). Subscribers can use this to reorder internal structures or update UI bindings accordingly.

TemplateChannelListSelectionChangedEvent

• Type: class
• Inherits: PubSubEvent<IGroupTemplateChannel>
• Behavior: Published when the selection state of a channel in the list changes (e.g., user selects/deselects a channel). The payload is the channel whose selection status changed.

TemplateChannelListRequiredChangedEvent

• Type: class
• Inherits: PubSubEvent<TemplateChannelListRequiredChangeEventArgs>
• Behavior: Published when the required status of one or more channels changes (e.g., a channel becomes mandatory or optional). The payload is a TemplateChannelListRequiredChangeEventArgs object containing:
  • Consumer: The object (e.g., view model or service) triggering the change.
  • Channels: An array of IGroupTemplateChannel instances whose required status has changed.

TemplateChannelListRequiredChangeEventArgs

• Type: class
• Properties:
  • public object Consumer { get; } — The entity initiating the required-status change.
  • public IGroupTemplateChannel[] Channels { get; } — The channels affected by the required-status change.
• Constructor:

  public TemplateChannelListRequiredChangeEventArgs(object o, IGroupTemplateChannel[] channels)
  

  Initializes the args with the specified consumer and channel array.

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3. Invariants

• All events are asynchronous (via Prism’s PubSubEvent), so ordering of delivery to subscribers is not guaranteed.
• The IGroupTemplateChannel type is assumed to represent a single channel with identity, name, and state (e.g., selection, required flag), but its exact contract is defined externally (see Dependencies).
• For TemplateChannelListOrderChangedEvent and TemplateChannelListSelectionChangedEvent, only one channel is emitted per event—no batch semantics are implied.
• For TemplateChannelListRequiredChangedEvent, the Channels array may contain zero or more channels, but the event is only published when at least one channel’s required status changes.
• The Consumer field in TemplateChannelListRequiredChangeEventArgs is not validated—it may be null, though this is discouraged.

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4. Dependencies

Dependencies of this module:

• Prism.Events — Provides the base PubSubEvent<T> class.
• DTS.Common.Interface.GroupTemplate.IGroupTemplateChannel — Defines the interface for channel objects. Its contract is assumed to include properties like IsSelected, IsRequired, and identity (e.g., Id), but this is not visible in the source.

Dependencies on this module:

• Any component managing or reacting to channel list state (e.g., UI views, view models, or services in the DTS.Common or higher layers) will subscribe to these events.
• The TemplateChannelListRequiredChangedEvent suggests integration with a consumer registration pattern (via the Consumer property), implying downstream systems track which entities are responsible for channel requirements.

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5. Gotchas

• Misleading documentation: All three events’ XML comments incorrectly state “called when a template is selected”—this is inconsistent with their actual payloads and naming. This may cause confusion during debugging or onboarding.
• Ambiguous semantics of Consumer: The Consumer field in TemplateChannelListRequiredChangeEventArgs is typed as object, offering no compile-time safety or clarity about expected types. This increases the risk of runtime errors if consumers misidentify the source of the change.
• No distinction between initiator and affected channels: In TemplateChannelListRequiredChangedEvent, the Consumer and Channels are bundled together, but it is unclear whether all channels in the array changed because of the consumer or for the consumer. This could lead to incorrect assumptions about causality.
• No event for bulk operations: If multiple channels’ order or selection changes simultaneously (e.g., drag-and-drop reordering of several items), this module provides no event to signal the full set—only per-channel events. Subscribers must deduce batch changes by correlating events, which is error-prone.
• No cancellation or rollback mechanism: These are notification-only events (fire-and-forget). There is no way for subscribers to veto a change (e.g., prevent an invalid reordering).

None identified beyond the above.