docs/scalus/scalus.compiler/OnChainSubstitute

OnChainSubstitute

scalus.compiler.OnChainSubstitute

final class OnChainSubstitute(substitute: AnyRef, selfAs: Class[_] = ...) extends StaticAnnotation

Marks a trait/class as having an on-chain substitute object.

When the Scalus plugin compiles a method call on a type annotated with @OnChainSubstitute, it redirects the call to the substitute @Compile object. The substitute object must define methods matching the original trait's methods, with an additional self first parameter.

On-chain, self receives the actual qualifier value (cast via typeProxy if selfAs is specified). Off-chain, the trait works as normal OOP — the annotation is ignored.

Value parameters

selfAs

The on-chain type for self. The plugin inserts a zero-cost typeProxy cast from the trait type to selfAs. Defaults to Nothing (no cast, self keeps the original type). Example:

@OnChainSubstitute(OnChainCellOps, classOf[ScriptContext])
trait CellContext {
 def requireSignedBy(pkh: PubKeyHash): Unit
}
@Compile
object OnChainCellOps {
 def requireSignedBy(self: ScriptContext, pkh: PubKeyHash): Unit =
     require(self.txInfo.isSignedBy(pkh), "missing signature")
}

substitute

A @Compile object providing on-chain implementations for each trait method.

Attributes

Graph
Supertypes: trait StaticAnnotation

class Annotation

class Object

trait Matchable

class Any

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