How must path variable counts match parameters in EK9 services?

  findItem() as GET for :/{catId}/{itemId}
    ->
      catId as Integer
      itemId as Integer
    <- response as HTTPResponse: ...

defines module qa.services.path.matching

  defines constant

    JSON_CONTENT <- "application/json"

  defines class

    <?-
      Models a catalog item found by category and item identifiers.
      Demonstrates how multi-segment path variables map to parameters.
    -?>
    CatalogItem
      categoryId as Integer: 0
      itemId as Integer: 0
      contentKind as String: JSON_CONTENT

      CatalogItem()
        ->
          givenCategoryId as Integer
          givenItemId as Integer
        this.categoryId :=: givenCategoryId
        this.itemId :=: givenItemId

      categoryId()
        <- rtn as Integer: Integer(categoryId)

      itemId()
        <- rtn as Integer: Integer(itemId)

      contentKind()
        <- rtn as String: String(contentKind)

      toJson()
        <- rtn as String: `{"cat": ${categoryId}, "item": ${itemId}}`

      operator $ as pure
        <- rtn as String: `CatalogItem[${categoryId}, ${itemId}]`
      operator #^ as pure
        <- rtn as String: $this
      default operator ?

    <?-
      Simulates a catalog endpoint with multi-segment path binding.
      In real services: GET /catalog/{catId}/{itemId} requires two parameters.
      The compiler validates path variable count matches parameter count (E07730).
    -?>
    CatalogEndpoint

      findItem()
        ->
          catId as Integer
          itemId as Integer
        <- rtn as CatalogItem: CatalogItem(catId, itemId)

      operator $ as pure
        <- rtn as String: "CatalogEndpoint"
      operator #^ as pure
        <- rtn as String: $this
      default operator ?

  defines program

    ServicePathMatchingDemo()
      stdout <- Stdout()
      endpoint <- CatalogEndpoint()
      catalogResult <- endpoint.findItem(10, 25)

      stdout.println("Path matching rules:")
      stdout.println("  URI variables must match parameter count")
      stdout.println("  GET /catalog/{catId}/{itemId} -> 2 params")
      stdout.println(catalogResult.toJson())