*BREAKING* Introduces BaseRenderContext.remember and stable eventHandlers.
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workflow-runtime/src/commonMain/kotlin/com/squareup/workflow1/internal/RealRenderContext.kt
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workflow-core/src/commonMain/kotlin/com/squareup/workflow1/BaseRenderContext.kt
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BaseRenderContext.remember and stable eventHandlers.
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zach-klippenstein
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Mar 10, 2025
| /** | ||
| * Convenience alias for working with [WorkflowAction.Updater]. | ||
| */ | ||
| public typealias Updater<P, S, O> = WorkflowAction<P, S, O>.Updater |
| * [props][PropsT] received from its parent, and it may render child workflows that do have | ||
| * their own internal state. | ||
| */ | ||
| public inline fun <PropsT, OutputT, RenderingT> Workflow.Companion.stateless( |
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Not related to this change, but did we end up discouraging the use of these functions?
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Nope. They're not super widely used but they're very handy when they're handy.
workflow-core/src/commonMain/kotlin/com/squareup/workflow1/BaseRenderContext.kt
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| private fun checkNotFrozen(reason: () -> String = { "" }) = check(!frozen) { | ||
| "RenderContext cannot be used after render method returns" + | ||
| "${reason().takeUnless { it.isBlank() }?.let { " ($it)" }}" |
…andlers`. Workflow makes it very convenient to render view models with anonymous lambdas as their event handler functions. Compose hates that. To address that mismatch without forcing everyone to retrofit their apps to use event objects instead of lambdas (it's a little late for that!) we introduce support for stable event handlers: anonymous lambdas whose identity looks the same to Compose across updates. In order to do this we're breaking the existing `eventHandler` and `safeEventHandler` functions a bit. - We introduce a new optional `remember: Boolean? = null` parameter. Set that true to get the new stability. If you leave it to the default `null` we look for a new `STABLE_EVENT_HANDLER : RuntimeConfigOption` to decide what to do. If you set that config option on an existing app and make no other changes, all of your existing `eventHandler` functions will be stable. - When `remember` is true, the existing `name` parameter becomes weight bearing. It's no longer just a logging aid, it's part of a key identifying your stable lambda. The other parts of the key are its return type, and the types of any of its parameters. Duplicating a key within a particular `render()` call is a runtime error, similar to the rules for `renderChild`, `runningWorker`, and `runningSideEffect`. - To make it easier to find fix and prevent those new runtime errors `testRender` and `WorkflowTestParams` now accept optional `RuntimeConfig` parameters, and throw appropriate errors if `STABLE_EVENT_HANDLER` is set. `testRender` also now honors `JvmTestRuntimeConfigTools.getTestRuntimeConfig()`. - Most of the `eventHandler` functions have also been changed to `inline` -- necessary so that we can reify their parameter types for the key scheme described above All of this is built on a new `BaseRenderContext.remember` primitive, which provides a light weight mechanism to save a bit of state across a workflow session without having to find room for it in `StateT`. `BaseRenderContext` also now provides `val runtimeConfig: RuntimeConfig` in support of all of the above.
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...samples/src/main/java/com/squareup/sample/compose/inlinerendering/InlineRenderingWorkflow.kt
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| .using(SizeTransform(clip = false)) | ||
| } | ||
| }, | ||
| label = "" |
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I think this fixed a compiler warning? Will check.
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Nope, seems to serve no purpose, will revert.
| * [props][PropsT] received from its parent, and it may render child workflows that do have | ||
| * their own internal state. | ||
| */ | ||
| public inline fun <PropsT, OutputT, RenderingT> Workflow.Companion.stateless( |
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Nope. They're not super widely used but they're very handy when they're handy.
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Workflow makes it very convenient to render view models with anonymous lambdas as their event handler functions. Compose hates that.
To address that mismatch without forcing everyone to retrofit their apps to use event objects instead of lambdas (it's a little late for that!) we introduce support for stable event handlers: anonymous lambdas whose identity looks the same to Compose across updates.
In order to do this we're breaking the existing
eventHandlerandsafeEventHandlerfunctions a bit.We introduce a new optional
remember: Boolean? = nullparameter. Set that true to get the new stability. If you leave it to the defaultnullwe look for a newSTABLE_EVENT_HANDLER : RuntimeConfigOptionto decide what to do. If you set that config option on an existing app and make no other changes, all of your existingeventHandlerfunctions will be stable.When
rememberis true, the existingnameparameter becomes weight bearing. It's no longer just a logging aid, it's part of a key identifying your stable lambda. The other parts of the key are its return type, and the types of any of its parameters. Duplicating a key within a particularrender()call is a runtime error, similar to the rules forrenderChild,runningWorker, andrunningSideEffect.To make it easier to find fix and prevent those new runtime errors,
testRenderandWorkflowTestParamsnow accept optionalRuntimeConfigparameters, and throw appropriate errors ifSTABLE_EVENT_HANDLERis set.testRenderalso now honorsJvmTestRuntimeConfigTools.getTestRuntimeConfig().Most of the
eventHandlerfunctions have also been changed toinline-- necessary so that we can reify their parameter types for the key scheme described aboveAll of this is built on a new
BaseRenderContext.rememberprimitive, which provides a light weight mechanism to save a bit of state across a workflow session without having to find room for it inStateT.BaseRenderContextalso now providesval runtimeConfig: RuntimeConfigin support of all of the above.