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create-capability-pact-guard

Use create-capability-pact-guard to create a predicate function that ensures that specific conditions are true and can be enforced to grant the specified CAPABILITY for steps defined in a defpact multi-step transaction.

By convention, capabilities are defined using all uppercase letters.

Basic syntax​

To create a predicate function that guards the specified CAPABILITY in a defpact multi-step transaction, use the following syntax:

(create-capability-pact-guard CAPABILITY)

Arguments​

Use the following argument to specify the CAPABILITY for the create-capability-pact-guard Pact function.

ArgumentTypeDescription
CAPABILITYcapabilitySpecifies the capability that the predicate function guards.

Return value​

The create-capability-pact-guard function returns a guard that enables the code associated with the specified CAPABILITY to be executed in the context of a defpact multi-step transaction.

Examples​

The following example demonstrates how to use the create-capability-pact-guard function to create a guard for the ESCROW owner capability in adefpact step:

(create-capability-pact-guard (ESCROW owner))

The following example creates a guard for the SALE_PRIVATE capability associated with the pact-id for the sales contract being executed:

  (defun offer:bool
    ( id:string
      seller:string
      amount:decimal
    )
    @doc "Initiate sale with by SELLER by escrowing AMOUNT of TOKEN until TIMEOUT."
    @model
      [ (property (!= id ""))
        (property (!= seller ""))
        (property (>= amount 0.0))
      ]
    (require-capability (SALE_PRIVATE (pact-id)))
    (let
      (
        (sender (debit id seller amount))
        (receiver (credit id (sale-account) (create-capability-pact-guard (SALE_PRIVATE (pact-id))) amount))
      )
      (emit-event (TRANSFER id seller (sale-account) amount))
      (emit-event (RECONCILE id amount sender receiver)))
  )