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Transaction policies

docs/src/calling-contracts/tx-policies.md

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Transaction policies

<!-- This section should explain what tx policies are and how to configure them --> <!-- tx_policies:example:start -->

Transaction policies are defined as follows:

rust,ignore
{{#include ../../../packages/fuels-core/src/types/wrappers/transaction.rs:tx_policies_struct}}

Where:

  1. Tip - amount to pay the block producer to prioritize the transaction.
  2. Witness Limit - The maximum amount of witness data allowed for the transaction.
  3. Maturity - Block until which the transaction cannot be included.
  4. Expiration - Block after which the transaction cannot be included.
  5. Max Fee - The maximum fee payable by this transaction.
  6. Script Gas Limit - The maximum amount of gas the transaction may consume for executing its script code.

When the Script Gas Limit is not set, the Rust SDK will estimate the consumed gas in the background and set it as the limit.

If the Witness Limit is not set, the SDK will set it to the size of all witnesses and signatures defined in the transaction builder.

You can configure these parameters by creating an instance of TxPolicies and passing it to a chain method called with_tx_policies:

<!-- tx_policies:example:end-->
rust,ignore
{{#include ../../../examples/contracts/src/lib.rs:tx_policies}}
<!-- This section should explain how to use the default tx policy --> <!-- tx_policies_default:example:start -->

You can also use TxPolicies::default() to use the default values.

<!-- tx_policies_default:example:end -->

This way:

rust,ignore
{{#include ../../../examples/contracts/src/lib.rs:tx_policies_default}}

As you might have noticed, TxPolicies can also be specified when deploying contracts or transferring assets by passing it to the respective methods.