Abstract contracts in Solidity

Leave a hole a child must fill.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

// An abstract contract leaves a hole a child must fill.
abstract contract Stand {
    uint256 public sold;

    function price() public pure virtual returns (uint256);

    function sell(uint256 n) external {
        sold += n * price();
    }
}

contract AppleStand is Stand {
    function price() public pure override returns (uint256) {
        return 3;
    }
}

How it works

1. abstract contract Stand cannot deploy alone.
2. price() is declared virtual with no body.
3. AppleStand overrides it and becomes deployable.

Keywords and builtins used here

• contract
• external
• function
• is
• public
• return
• returns
• uint256

The run, in numbers

Lines

19

Characters to type

384

Tokens

67

Three-star pace

60 tpm

At the three-star pace of 60 tokens a minute, this run takes about 67 seconds.

Type this snippet

Step 3 of 4 in Composition, step 19 of 28 in Language basics.

← Previous Next →