Reduce the number of checks and special code paths in Fusion (#418)

docs/api-reference/general/errors.md

@@ -151,24 +151,6 @@ be designed to have dependents or dependencies.
 
 <div class="fusiondoc-error-api-section" markdown>
 
-## cleanupWasRenamed
-
-```
-`Fusion.cleanup` was renamed to `Fusion.doCleanup`. This will be an error in
-future versions of Fusion.
-```
-
-**Thrown by:**
-[`doCleanup`](../../memory/members/docleanup)
-
-You attempted to use `cleanup()` in Fusion 0.3, which replaces it with the
-`doCleanup()` method.
-</div>
-
------
-
-<div class="fusiondoc-error-api-section" markdown>
-
 ## destroyedTwice
 
 ```
@@ -197,34 +179,6 @@ cleaning up the scope.
 
 <div class="fusiondoc-error-api-section" markdown>
 
-## destructorRedundant
-
-```
-Computed destructors no longer do anything. If you wish to run code on destroy,
-`table.insert` a function into the `scope` argument. See discussion #292 on
-GitHub for advice.
-```
-
-**Thrown by:**
-[`Computed`](../../state/members/computed),
-[`ForKeys`](../../state/members/forkeys),
-[`ForValues`](../../state/members/forvalues),
-[`ForPairs`](../../state/members/forpairs)
-
-**Related discussions:** 
-[`#292`](https://github.com/dphfox/Fusion/discussions/292)
-
-You passed an extra parameter to the constructor, which has historically been
-interpreted as a function that runs when a value is cleaned up.
-
-This mechanism has been replaced by
-[scopes](../../../tutorials/fundamentals/scopes).
-</div>
-
------
-
-<div class="fusiondoc-error-api-section" markdown>
-
 ## forKeyCollision
 
 ```
@@ -371,23 +325,6 @@ type.
 
 <div class="fusiondoc-error-api-section" markdown>
 
-## invalidRefType
-
-```
-Instance refs must be Value objects.
-```
-
-**Thrown by:**
-[`Ref`](../../roblox/members/ref)
-
-`Ref` expected you to give it a [value](../../state/members/value), but you gave
-it something else.
-</div>
-
------
-
-<div class="fusiondoc-error-api-section" markdown>
-
 ## invalidSpringDamping
 
 ```
@@ -533,54 +470,6 @@ reference to it, as it is no longer valid.
 
 <div class="fusiondoc-error-api-section" markdown>
 
-## possiblyOutlives
-
-```
-The Computed (bound to the PaddingLeft property) will be destroyed before the 
-UIPadding instance; the latter is in a different scope that gets destroyed too 
-quickly. To fix this, review the order they're created in, and what scopes they 
-belong to. See discussion #292 on GitHub for advice. 
-```
-
-**Thrown by:**
-[`Spring`](../../animation/members/spring),
-[`Tween`](../../animation/members/tween),
-[`New`](../../roblox/members/new),
-[`Hydrate`](../../roblox/members/hydrate),
-[`Attribute`](../../roblox/members/attribute),
-[`AttributeOut`](../../roblox/members/attributeout),
-[`Out`](../../roblox/members/out),
-[`Ref`](../../roblox/members/ref),
-[`Computed`](../../state/members/computed),
-[`Observer`](../../graph/members/observer)
-
-**Related discussions:** 
-[`#292`](https://github.com/dphfox/Fusion/discussions/292)
-
-If you use an object after it's been destroyed, then your code can break. This
-mainly happens when one object 'outlives' another object that it's using.
-
-Because [scopes](../../../tutorials/fundamentals/scopes) clean up the newest
-objects first, this can happen when an old object depends on something much
-newer that itself. During cleanup, a situation could arise where the newer
-object is destroyed, then the older object runs code of some kind that needed
-the newer object to be there.
-
-Fusion can check for situations like this by analysing the scopes. This message
-is shown when Fusion can prove one of these situations will occur.
-
-There are two typical solutions:
-
-- If the objects should always be created and destroyed at the exact same time,
-then ensure they're created in the correct order.
-- Otherwise, move the objects into separate scopes, and ensure that both scopes
-can exist without the other scope.
-</div>
-
------
-
-<div class="fusiondoc-error-api-section" markdown>
-
 ## propertySetError
 
 ```
@@ -602,39 +491,6 @@ issue.
 
 <div class="fusiondoc-error-api-section" markdown>
 
-## scopeMissing
-
-```
-To create Observers, provide a scope. (e.g. `myScope:Observer(watching)`). See
-discussion #292 on GitHub for advice.
-```
-
-**Thrown by:**
-[`New`](../../roblox/members/new),
-[`Hydrate`](../../roblox/members/hydrate),
-[`Value`](../../state/members/value),
-[`Computed`](../../state/members/computed),
-[`Observer`](../../graph/members/observer),
-[`ForKeys`](../../state/members/forkeys),
-[`ForValues`](../../state/members/forvalues),
-[`ForPairs`](../../state/members/forpairs),
-[`Spring`](../../animation/members/spring),
-[`Tween`](../../animation/members/tween)
-
-**Related discussions:** 
-[`#292`](https://github.com/dphfox/Fusion/discussions/292)
-
-You attempted to create an object without providing a
-[scope](../../../tutorials/fundamentals/scopes) as the first parameter.
-
-Scopes are mandatory for all Fusion constructors so that Fusion knows when the
-object should be destroyed.
-</div>
-
------
-
-<div class="fusiondoc-error-api-section" markdown>
-
 ## springNanGoal
 
 ```
@@ -696,36 +552,6 @@ is currently outputting. However, you provided a different data type.
 
 <div class="fusiondoc-error-api-section" markdown>
 
-## stateGetWasRemoved
-
-```
-`StateObject:get()` has been replaced by `use()` and `peek()` - see discussion
-#217 on GitHub.
-```
-
-**Thrown by:**
-[`Value`](../../state/members/value),
-[`Computed`](../../state/members/computed),
-[`ForKeys`](../../state/members/forkeys),
-[`ForValues`](../../state/members/forvalues),
-[`ForPairs`](../../state/members/forpairs),
-[`Spring`](../../animation/members/spring),
-[`Tween`](../../animation/members/tween)
-
-**Related discussions:** 
-[`#217`](https://github.com/dphfox/Fusion/discussions/217)
-
-Older versions of Fusion let you call `:get()` directly on state objects to read
-their current value and attempt to infer dependencies.
-
-This has been replaced by [use functions](../../state/types/use) in Fusion 0.3
-for more predictable behaviour and better support for constant values.
-</div>
-
------
-
-<div class="fusiondoc-error-api-section" markdown>
-
 ## tweenNanGoal
 
 ```
@@ -860,7 +686,6 @@ is use()-ing. See discussion #292 on GitHub for advice.
 [`Attribute`](../../roblox/members/attribute),
 [`AttributeOut`](../../roblox/members/attributeout),
 [`Out`](../../roblox/members/out),
-[`Ref`](../../roblox/members/ref),
 [`Computed`](../../state/members/computed),
 [`Observer`](../../graph/members/observer)
 

src/Animation/Spring.luau

@@ -64,9 +64,6 @@ local function Spring<T>(
 	damping: Types.UsedAs<number>?
 ): Types.Spring<T>
 	local createdAt = os.clock()
-	if typeof(scope) ~= "table" or castToState(scope) ~= nil then
-		External.logError("scopeMissing", nil, "Springs", "myScope:Spring(goalState, speed, damping)")
-	end
 
 	local goalState = castToState(goal)
 	local stopwatch = nil
@@ -165,12 +162,6 @@ function class.addVelocity<T>(
 	change(self)
 end
 
-function class.get<T>(
-	self: Self<T>
-): never
-	return External.logError("stateGetWasRemoved")
-end
-
 function class.setPosition<T>(
 	self: Self<T>,
 	newValue: T

src/Animation/Tween.luau

@@ -54,9 +54,6 @@ local function Tween<T>(
 	tweenInfo: Types.UsedAs<TweenInfo>?
 ): Types.Tween<T>
 	local createdAt = os.clock()
-	if castToState(scope) then
-		External.logError("scopeMissing", nil, "Tweens", "myScope:Tween(goalState, tweenInfo)")
-	end
 
 	local goalState = castToState(goal)
 	local stopwatch = nil
@@ -118,12 +115,6 @@ local function Tween<T>(
 	return self
 end
 
-function class.get<T>(
-	self: Self<T>
-): never
-	return External.logError("stateGetWasRemoved")
-end
-
 function class._evaluate<T>(
 	self: Self<T>
 ): boolean

src/External.luau

@@ -16,11 +16,6 @@ local ERROR_INFO_URL = "https://elttob.uk/Fusion/0.3/api-reference/general/error
 
 local External = {}
 
--- Indicates that a highly time-critical passage of code is running. During
--- critical periods of a program, Fusion might decide to change some of its
--- internal behaviour to be more performance friendly.
-local timeCritical = false
-
 -- Multiplier for running-time safety checks across the Fusion codebase. Used to
 -- stricten tests on infinite loop detection during unit testing.
 External.safetyTimerMultiplier = 1
@@ -47,13 +42,6 @@ function External.setExternalProvider(
 	return oldProvider
 end
 
---[[
-	Returns true if a highly time-critical passage of code is running.
-]]
-function External.isTimeCritical(): boolean
-	return timeCritical
-end
-
 --[[
    Sends an immediate task to the external provider. Throws if none is set.
 ]]

src/Graph/Observer.luau

@@ -38,9 +38,6 @@ local function Observer(
 	watching: unknown
 ): Types.Observer
 	local createdAt = os.clock()
-	if watching == nil then
-		External.logError("scopeMissing", nil, "Observers", "myScope:Observer(watching)")
-	end
 
 	local self: Self = setmetatable(
 		{

src/Instances/Hydrate.luau

@@ -10,16 +10,12 @@ local task = nil -- Disable usage of Roblox's task scheduler
 
 local Package = script.Parent.Parent
 local Types = require(Package.Types)
-local External = require(Package.External)
 local applyInstanceProps = require(Package.Instances.applyInstanceProps)
 
 local function Hydrate(
 	scope: Types.Scope<unknown>,
 	target: Instance
 )
-	if target :: any == nil then
-		External.logError("scopeMissing", nil, "instances using Hydrate", "myScope:Hydrate (instance) { ... }")
-	end
 	return function(
 		props: Types.PropertyTable
 	): Instance

src/Instances/New.luau

@@ -20,11 +20,6 @@ local function New(
 	scope: Types.Scope<unknown>,
 	className: string
 )
-	if (className :: any) == nil then
-		local scope = (scope :: any) :: string
-		External.logError("scopeMissing", nil, "instances using New", "myScope:New \"" .. scope .. "\" { ... }")
-	end
-
 	-- This might look appealing to try and cache. But please don't. The scope
 	-- upvalue is shared between the two curried function calls, so this will
 	-- open incredible cross-codebase wormholes like you've never seen before.

src/Logging/messages.luau

@@ -14,9 +14,7 @@ return {
 	cannotConnectEvent = "The %s class doesn't have an event called '%s'.",
 	cannotCreateClass = "Can't create a new instance of class '%s'.",
 	cannotDepend = "%s can't depend on %s.",
-	cleanupWasRenamed = "`Fusion.cleanup` was renamed to `Fusion.doCleanup`. This will be an error in future versions of Fusion.",
 	destroyedTwice = "`doCleanup()` was given something that it is already cleaning up. Unclear how to proceed.",
-	destructorRedundant = "%s destructors no longer do anything. If you wish to run code on destroy, `table.insert` a function into the `scope` argument. See discussion #292 on GitHub for advice.",
 	forKeyCollision = "The key '%s' was returned multiple times simultaneously, which is not allowed in `For` objects.",
 	infiniteLoop = "Detected an infinite loop. Consider adding an explicit breakpoint to your code to prevent a cyclic dependency.",
 	invalidAttributeChangeHandler = "The change handler for the '%s' attribute must be a function.",
@@ -26,7 +24,6 @@ return {
 	invalidOutProperty = "The %s class doesn't have a property called '%s'.",
 	invalidOutType = "[Out] properties must be given Value objects.",
 	invalidPropertyType = "'%s.%s' expected a '%s' type, but got a '%s' type.",
-	invalidRefType = "Instance refs must be Value objects.",
 	invalidSpringDamping = "The damping ratio for a spring must be >= 0. (damping was %.2f)",
 	invalidSpringSpeed = "The speed of a spring must be >= 0. (speed was %.2f)",
 	mergeConflict = "Multiple definitions for '%s' found while merging.",
@@ -35,13 +32,10 @@ return {
 	mistypedTweenInfo = "The tween info of a tween must be a TweenInfo. (got a %s)",
 	noTaskScheduler = "Fusion is not connected to an external task scheduler.",
 	poisonedScope = "Attempted to use a scope after it's been destroyed; %s",
-	possiblyOutlives = "%s will be destroyed before %s; %s. To fix this, review the order they're created in, and what scopes they belong to. See discussion #292 on GitHub for advice.",
 	propertySetError = "Error setting property:\nERROR_MESSAGE",
-	scopeMissing = "To create %s, provide a scope. (e.g. `%s`). See discussion #292 on GitHub for advice.",
 	springNanGoal = "A spring was given a NaN goal, so some simulation has been skipped. Ensure no springs have NaN goals.",
 	springNanMotion = "A spring encountered NaN during motion, so has snapped to the goal position. Ensure no springs have NaN positions or velocities.",
 	springTypeMismatch = "The type '%s' doesn't match the spring's type '%s'.",
-	stateGetWasRemoved = "`StateObject:get()` has been replaced by `use()` and `peek()` - see discussion #217 on GitHub.",
 	tweenNanGoal = "A tween was given a NaN goal, so some animation has been skipped. Ensure no tweens have NaN goals.",
 	tweenNanMotion = "A tween encountered NaN during motion, so has snapped to the goal. Ensure no tweens have NaN in their tween infos.",
 	unknownMessage = "Unknown error:\nERROR_MESSAGE",

src/Memory/checkLifetime.luau

@@ -12,7 +12,6 @@ local task = nil -- Disable usage of Roblox's task scheduler
 local Package = script.Parent.Parent
 local Types = require(Package.Types)
 local External = require(Package.External)
-local whichLivesLonger = require(Package.Memory.whichLivesLonger)
 local nameOf = require(Package.Utility.nameOf)
 
 local checkLifetime = {}
@@ -119,16 +118,7 @@ function checkLifetime.bOutlivesA<A, B, Args...>(
 )
 	if scopeB == nil then
 		External.logError("useAfterDestroy", nil, formatter(a, b, ...))
-	elseif whichLivesLonger(scopeA, a, scopeB, b) == "definitely-a" then
-		local aName, bName = formatter(a, b, ...)
-		External.logWarn(
-			"possiblyOutlives",
-			aName, bName, 
-			if scopeA == scopeB then
-				"they're in the same scope, but the latter is destroyed too quickly"
-			else
-				"the latter is in a different scope that gets destroyed too quickly"
-		)
 	end
 end
+
 return checkLifetime