Ethereum Cookbook

Abstract contracts

1. Create abstract contracts just like regular contracts, but they have at least one function without an implementation:

pragma solidity ^0.4.24;contract AbstractContrct {    // Function without declaration    function f() public returns (uint);    // Function with declaration    function c() public returns (uint) {        return 0;    }}

2. Abstracted contracts cannot be compiled. Use it as a base contract while inheriting. The inherited contracts will only compile if it implements all non-implemented functions by overriding:

pragma solidity ^0.4.24;// Abstract contractcontract AbstractContrct {    function f() public returns (uint);}// Contract with functions implementedcontract InheritedContract is AbstractContrct { function f() public returns ...