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Differences from other DI frameworks

…from Dagger

  • There is no @Module. All providers run through graphs and their supertypes.
  • There is no Producers support.
  • There is no Hilt support, though some features are similar in the same way that Anvil’s features are similar.
  • There is no @Reusable.
  • There is no @BindsOptionalOf. Instead, Metro supports default optional dependencies.
  • There is no @Subcomponent. Instead, Metro uses graph extensions.
  • Metro can inject private properties and functions.
  • There is no @BindsInstance. Use @Provides on @DependencyGraph.Factory function parameters instead
  • Component dependencies must be annotated with @Includes.
  • Metro does not process Java code.
  • @Multibinds declarations are implemented in Metro graphs to return the declared multibinding.
  • Empty multibindings are an error by default in Metro. To allow a multibinding to be empty, it must be declared with @Multibinds(allowEmpty = true).

…from Kotlin-Inject

  • typealiases are not treated as implicit qualifiers.
  • Dependency graph classes cannot have primary constructors, their parameters must be defined as @Provides or graph parameters on a @DependencyGraph.Factory function like Dagger.
  • Higher order functions cannot be used. Instead, use Provider and declared @AssistedFactory-annotated types.
  • No need for use-site targets for most annotations.
  • No need for @get:Provides Impl.bind: Type get() = this to achieve type bindings. See the docs on @Binds.
  • Metro can inject private properties and functions.
  • When extending parent graphs, they must be annotated with @Extends in the child graph’s creator.
  • Metro does not process Java code.

…from Anvil

  • There is no rank in Metro’s @Contributes* annotations.
    • Note that if Anvil interop is enabled, its rank properties are supported in interop.
  • @ContributesBinding uses a binding API to support generic bound types. See the aggregation docs for more info.
    • Note that if Anvil interop is enabled, its boundType properties are supported in interop.
  • @Contributes*.replaces cannot replace classes in the same compilation as the graph that is merging them

…from kotlin-inject-anvil

  • There is no need for @CreateComponent or expect fun createComponent() functions.
  • @ContributesBinding uses a binding API to support generic bound types. See the aggregation docs for more info.
    • Note that if Anvil interop is enabled, its boundType properties are supported in interop.
  • @Contributes*.replaces cannot replace classes in the same compilation as the graph that is merging them