Lines 3–6: Defines an interface named IAnimal
.
Line 4: Declares a function signature setAge
with one parameter _age
of type uint256
. This function does not have any implementation details and is marked as external
.
Line 5: Declares a function signature getAge
with no parameters. It specifies that this function is external
and view
, meaning it does not modify the contract’s state and returns a value of type uint256
.
Lines 8–21: Declares a contract named Animal
that implements the IAnimal
interface.
Line 9: Declares a private state variable age
of type uint256
to store the age of the animal.
Line 11: Declares an event named AgeSet
with one parameter newAge
of type uint256
. This event will be emitted whenever the age of the animal is set.
Lines 13–16: Defines a function setAge
that takes one parameter _age
of type uint256
. This function is marked as external
, indicating it can be called from outside the contract.
Line 14: Assigns the value of _age
to the age
state variable.
Line 15: Emits the AgeSet
event with the parameter _age
, indicating that the animal’s age has been set.
Lines 18–20: Defines a function getAge
with no parameters. It is marked as external
and view
, indicating that it does not modify the contract’s state and can be called from outside the contract.
Line 19: Returns the value of the age
state variable.
Choosing between inheritance and interfaces
Inheritance and interfaces both provide ways to structure contracts in Solidity but serve different purposes based on the design needs of our application. Choosing the right one can enhance modularity, code reuse, and adherence to specific standards within your smart contract architecture.
Inheritance
Interfaces
Conclusion
In Solidity, inheritance, and interfaces are valuable tools for achieving code organization and reuse. The choice between them depends on the smart contract’s specific requirements and the desired level of abstraction. Developers often combine both to create modular, interoperable, and maintainable code.