Plugin for stages/state machine pattern

šŸ“œ Development Proposals
1

Stages pattern (also called state machine pattern: State Machine | solidity-patterns) is a pattern in smart contract development used to implement contracts which go through different phases.

Iā€™d like to implement stages pattern as a plugin in Cairo. Each stage would be a separate module. Additionally there would be a main contract which would hold common storage and functions. A plugin would then merge those modules into a proper cairo contract.

An example contract using the hypothetical plugin:

#[staged_contract]
mod Pool {
    use starknet::ContractAddress;

    // Common storage variables and functions
    struct Storage{
        owner: ContractAddress,
        max_contribution: u256
    }

    #[constructor]
    fn constructor(...){
        ...
    }
}

#[initial_stage(Pool)]
mod Initialization {
    fn transition(...) {
        // Transition to the next stage
        stage(Contribute);
    }
    
    // Storage variables and functions used only in this stage
    // If called in another stage the function will fail
    ...
}

#[stage(Pool)]
mod Contribute {
    fn transition(...) {
        stage(Collect);
    }

    ...
}

#[stage(Pool)]
mod Collect {
    // End state - no transitions
    ...
}

The main pros of the plugin are:

  • Less error-prone code
  • Easier manual analysis
  • Due to standardization and more declarative approach automatic tools could utilize the information about different stages and be aware of it

For example, utilizing the information one could build a tool to visualize staged contract as a state diagram showing transitions between stages, or a tool that yields a different ABI depending on current stage.

If the plugin proves to be useful some other patterns may also be implemented using a similar approach. For example, access restriction could be implemented in a way that each module represents an interface for a different role in the system.

Would you use such a plugin? Any feedback is appreciated!

2

Solid Info! Keep it Up!