Low-level calls

With low-level calls, you can specify the parameters of your calls at runtime and make indirect calls through other contracts.

Your caller contract should call std::low_level_call::call_with_function_selector, providing:

• target contract ID
• function selector encoded as Bytes
• calldata encoded as Bytes
• whether the calldata contains only a single value argument (e.g. a u64)
• std::low_level_call::CallParams

{{#include ../../../e2e/sway/contracts/low_level_caller/src/main.sw:low_level_call_contract}}

On the SDK side, you can construct an encoded function selector using fuels::core::encode_fn_selector, and encoded calldata using the fuels::core::calldata! macro.

E.g. to call the following function on the target contract:

{{#include ../../../e2e/sway/contracts/contract_test/src/main.sw:low_level_call}}

you would construct the function selector and the calldata as such, and provide them to the caller contract (like the one above):

{{#include ../../../examples/contracts/src/lib.rs:low_level_call}}

Note: the calldata! macro uses the default EncoderConfig configuration under the hood.