Instantiate

This is one of the most fundamental entrypoints. This entrypoint is called once during the contract lifecycle, right after an address has been assigned. It essentially is there to initialise the state of your contract (for example, initialising a counter in storage, etc.).

You can imagine it as the constructor of your contract.

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Note that this function is called for each instance of your contract that you decide to create, not one time ever.

To equate it to OOP, your contract is a class, and this is the constructor, and you can have multiple instances of the same class, and the constructor is called once for every one of these instances.

It is not a singleton.

Definition

contract.rs

#[cfg_attr(not(feature = "library"), entry_point)]
pub fn instantiate(
    _deps: DepsMut,
    _env: Env,
    _info: MessageInfo,
    _msg: InstantiateMsg,
) -> StdResult<Response> {
    // TODO: Initialise storage, send out metrics, do mischief
    Ok(Response::new())
}

Entrypoints Execute