Using with ktlint

Using with Kotlinter¶

If using kotlinter, you can specify the dependency on this set of rules by using the buildscript classpath.

buildscript {
    dependencies {
        classpath "io.nlopez.compose.rules:ktlint:<version>"
    }
}

Using with ktlint-gradle¶

Note: You need at least version 11.1.0 of this plugin.

If using ktlint-gradle, you can specify the dependency on this set of rules by using the ktlintRuleset.

dependencies {
    ktlintRuleset "io.nlopez.compose.rules:ktlint:<VERSION>"
}

Using with spotless¶

See Spotless Ktlint Integration.

Using with ktlint CLI or the ktlint IntelliJ plugin¶

The releases page contains an uber jar for each version release that can be used for these purposes. In the releases page you can identify them by the suffix -all.jar.

To use with ktlint CLI:

ktlint -R ktlint-compose-<VERSION>-all.jar

You can use this same uber jar from the releases page with the ktlint IntelliJ plugin if the rules are compiled against the same ktlint version used for that release. You can configure the custom ruleset in the preferences page of the plugin.

Supported versions matrix¶

Version	Ktlint version	Kotlin (Syntax)
0.4.23+	1.5.0	2.1.0
0.4.18+	1.4.1	2.0.21
0.4.17	1.4.0	2.0.21
0.4.12+	1.3.1	2.0.20
0.4.6+	1.3.1	2.0.0
0.4.5	1.3.0	2.0.0
0.3.12+	1.2.1	1.9.23
0.3.9+	1.1.1	1.9.22

Older version support can be found in the release notes.

Configuring rules¶

Providing custom content emitters¶

There are some rules (compose:content-emitter-returning-values-check, compose:modifier-not-used-at-root and compose:multiple-emitters-check) that use predefined list of known composables that emit content. But you can add your own too! In your .editorconfig file, you'll need to add a compose_content_emitters property followed by a list of composable names separated by commas. You would typically want the composables that are part of your custom design system to be in this list.

[*.{kt,kts}]
compose_content_emitters = MyComposable,MyOtherComposable

Providing exceptions to content emitters¶

Sometimes we'll want to not count a Composable towards the multiple content emitters (compose:multiple-emitters-check) rule. This is useful, for example, if the composable function actually emits content but that content is painted in a different window (like a dialog or a modal). For those cases, we can use a denylist compose_content_emitters_denyylist to add those composable names separated by commas.

[*.{kt,kts}]
compose_content_emitters_denylist = MyModalComposable,MyDialogComposable

Providing custom ViewModel factories¶

The vm-injection-check rule will check against common ViewModel factories (eg viewModel from AAC, weaverViewModel from Weaver, hiltViewModel from Hilt + Compose, etc), but you can configure your .editorconfig file to add your own, as a list of comma-separated strings:

[*.{kt,kts}]
compose_view_model_factories = myViewModel,potatoViewModel

Providing a list of allowed `CompositionLocal`s¶

For compositionlocal-allowlist rule you can define a list of CompositionLocals that are allowed in your codebase.

[*.{kt,kts}]
compose_allowed_composition_locals = LocalSomething,LocalSomethingElse

Ignore annotated functions with specific annotations for missing Modifier checks¶

In the modifier-missing-check rule, you can define a list of annotations that, if present, will make it so the function is exempt from this rule.

[*.{kt,kts}]
compose_modifier_missing_ignore_annotated = Potato,Banana

Allowing matching function names¶

The naming-check rule requires all composables that return a value to be lowercased. If you want to allow certain patterns though, you can configure a comma-separated list of matching regexes in your .editorconfig file:

[*.{kt,kts}]
compose_allowed_composable_function_names = .*Presenter,.*SomethingElse

Allowing custom state holder names¶

The vm-forwarding-check rule will, by default, design as a state holder any class ending on "ViewModel" or "Presenter". You can, however, add new types of names to the mix via a comma-separated list of matching regexes in your .editorconfig file:

[*.{kt,kts}]
compose_allowed_state_holder_names = .*ViewModel,.*Presenter,.*Component,.*SomethingElse

Allowlist for composable names that aren't affected by the ViewModelForwarding rule¶

The vm-forwarding-check will catch VMs/state holder classes that are relayed to other composables. However, in some situations this can be a valid use-case. The rule can be configured so that all the names of composables that match a list of regexes are exempt to this rule. You can configure this in your .editorconfig file:

[*.{kt,kts}]
compose_allowed_forwarding = .*Content,.*SomethingElse

Allowlist for ViewModel/state holder names that aren't affected by the ViewModelForwarding rule¶

The vm-forwarding-check will catch VMs/state holder classes that are relayed to other composables. However, in some situations this can be a valid use-case. The rule can be configured so that all the names of ViewModels that match a list of regexes are exempt to this rule. You can configure this in your .editorconfig file:

[*.{kt,kts}]
compose_allowed_forwarding_of_types = .*MyViewModel,PotatoViewModel

Configure the visibility of the composables where to check for missing modifiers¶

The modifier-missing-check rule will, by default, only look for missing modifiers for public composables. If you want to lower the visibility threshold to check also internal compoosables, or all composables, you can configure it in your .editorconfig file:

[*.{kt,kts}]
compose_check_modifiers_for_visibility = only_public

Possible values are:

only_public: (default) Will check for missing modifiers only for public composables.
public_and_internal: Will check for missing modifiers in both public and internal composables.
all: Will check for missing modifiers in all composables.

Configure custom Modifier names¶

Most of the modifier-related rules will look for modifiers based their type: either Modifier or GlanceModifier type. Some libraries might add their own flavor of Modifier to the mix, and it might make sense to enforce the same rules we have for the other default modifiers. To support that, you can configure this in your .editorconfig file:

[*.{kt,kts}]
compose_custom_modifiers = BananaModifier,PotatoModifier

Configure types to treat as lambdas (e.g. for ParamOrder check)¶

The param-order-check rule will do its best to identify trailing lambdas. However, in cases where a typedef / functional interface is being used, we might want to have this rule to treat them as if they were lambdas: not reporting them if they are the last in a method signature and they don't have a default value. To give ktlint some hints, you can configure this in your .editorconfig file:

[*.{kt,kts}]
compose_treat_as_lambda = MyLambdaType,MyOtherLambdaType

Configure types to treat as composable lambdas (e.g. for ContentTrailingLambda check)¶

The content-trailing-lambda rule will do its best to identify @Composable trailing lambdas. However, in cases where a typedef / functional interface is being used, we might want to have this rule to treat them as if they were composable lambdas: not reporting them if they are the last in a method signature and they don't have a default value. To give ktlint some hints, you can configure this in your .editorconfig file:

[*.{kt,kts}]
compose_treat_as_composable_lambda = MyLambdaComposableType,MyOtherComposableLambdaType

Enabling the Material 2 detector¶

The material-two rule will flag any usage of a Material 2 API. This rule is disabled by default, so you'll need to explicitly enable it in your .editorconfig file:

[*.{kt,kts}]
compose_disallow_material2 = true

You might also want to disallow Material 2, but allow a specific set / subset of APIs. The rule allows this too.

For example, let's say you want to allow all filled icons (whose fully qualified names are androidx.compose.material.icons.filled.*) and the Button composable (androidx.compose.material.Button). This is how you'd allow those:

[*.{kt,kts}]
compose_disallow_material2 = true
compose_allowed_from_m2 = icons.filled,Button

Enabling the unstable collections detector¶

The unstable-collections rule will flag any usage of any unstable collection (e.g. List/Set/Map). This rule is disabled by default, so you'll need to explicitly enable it in your .editorconfig file:

[*.{kt,kts}]
compose_disallow_unstable_collections = true

Enabling and configuring the preview naming detector¶

If you want to enforce a naming strategy for previews, you can enable the compose:preview-naming rule and configure the compose_preview_naming_strategy property in your .editorconfig file:

[*.{kt,kts}]
compose_preview_naming_enabled = true
compose_preview_naming_strategy = suffix

Possible values of compose_preview_naming_strategy are:

suffix: Previews should have Preview as suffix.
prefix: Previews should have Preview as prefix.
anywhere: Previews should contain Preview in their names.

Disable `standard:function-naming` rule for Composable¶

The function name for a Composable starts with an uppercase. This causes the ktlint rule standard:function-naming to report a violation. This rule can be configured to ignore Composable functions in your .editorconfig file:

[*.{kt,kts}]
ktlint_function_naming_ignore_when_annotated_with = Composable

Disabling a specific rule¶

To disable a rule you have to follow the instructions from the ktlint documentation, and use the id of the rule you want to disable with the compose tag.

For example, to disable the naming-check rule, the tag you'll need to disable is ktlint:compose:naming-check.

    @Suppress("ktlint:compose:naming-check")
    fun YourComposableHere() { ... }