[Perf] Lazy-initialize _triggerSpecificity dictionary on BindableObject

[simonrozsival]

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Fixes #34131

Description

The Dictionary<TriggerBase, SetterSpecificity> field _triggerSpecificity was eagerly allocated on every BindableObject instance, but fewer than 5% of objects ever use triggers. This PR makes it lazy-initialized on first use.

Changes

• BindableObject.cs — remove eager = new Dictionary<...>() initializer
• TriggerBase.cs — null-safe access at 3 call sites (??= on attach, ?. on detach, ?.TryGetValue on condition changed)

[MartyIX]

Would it work to add

#nullable enable

internal Dictionary<TriggerBase, SetterSpecificity>? _triggerSpecificity;

#nullable disable

?

Or would it still cascade to more and more changes?

[simonrozsival]

That should work, but I don't think it has high value right now. We should let copilot annotate the whole class/codebase at some point.

[Copilot]

Pull request overview

This PR optimizes memory allocation in BindableObject by lazy-initializing the _triggerSpecificity dictionary, which is only used by the small fraction of objects (<5%) that actually have triggers attached. This reduces per-instance allocations for the vast majority of MAUI UI elements.

Changes:

• Removed eager initialization of _triggerSpecificity dictionary in BindableObject
• Added null-safe operations at all three access points in TriggerBase (attach, detach, condition changed)
• Added comprehensive benchmarks to measure allocation improvements for objects without triggers

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/Controls/src/Core/BindableObject.cs	Removed eager = new Dictionary<...>() initializer from _triggerSpecificity field
src/Controls/src/Core/Interactivity/TriggerBase.cs	Added null-coalescing assignment on attach, conditional access on detach and condition query
src/Core/tests/Benchmarks/Benchmarks/BindableObjectAllocBenchmarker.cs	New benchmark file covering multiple performance issues including trigger dictionary allocation (#34131)