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How can I make my code sequential, meaning I'd like functions to be performed in a certain order.

Can I make a function not run able till another is run. An example would be great help.

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Here is an idiomatic example that forces functions to be called in a certain order. There is more than one way to do it. Functions check conditions to confirm the transaction is permissible.

pragma solidity 0.5.1;

contract Stages {

    enum Stage { init, two, three, done }

    Stage stage;

    modifier onlyStage (Stage s) {
        require(stage == s, "Wrong step.");
        _;
    }

    function step1() public onlyStage(Stage.init) {
        // do something
        stage = Stage.two;
    }

    function step2() public onlyStage(Stage.two) {
        // do something
        stage = Stage.three;
    }

    function step3() public onlyStage(Stage.three) {
        // do something
        stage = Stage.done;
    }
}

In practice, you would probably have multiple transactions, each at their own stage. For example, a contract to run a game could control multiple games simultaneously. Each game would have properties such as the players, any stake and/or scores, and possibly who's turn it is to play next.

The question is sort of open-ended, so it bears mentioning that any time a function calls out to other contract functions, you are assured that those functions will run in order.

contract A {
  ...
  function inOrder() public {
    b.step1();
    b.step2();
    c.somethingElse(); // step 3
  }
}

Hope it helps.

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Sounds like you want to use a state machine pattern.

Have a read of the Solidity docs, here.

Contracts often act as a state machine, which means that they have certain stages in which they behave differently or in which different functions can be called. A function call often ends a stage and transitions the contract into the next stage (especially if the contract models interaction).

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