Quick Guide To Solidity Interfaces

In this article, we’ll take a closer look at Solidity interfaces and explore how they can be used to create flexible and modular contract designs.



Solidity Interface

Solidity interface is the same thing as an abstract contract created with the interface keyword.

There are no state variables, constructors, or functions with implementations. Instead, they only contain declarations of functions, i.e. interface functions are not statements.

Interface functions can only have external types. It is possible to inherit from other interfaces, but not from other contracts.

There can be enums and structs in interfaces, which can be accessed using interface name dot notation.

The following example will help you to understand the concept of interfaces and their use:

Example: 

pragma solidity ^0.8.0;interface SolidityTest{ // Here we declare an interfacefunction get_String(string memory mrx) external view returns(string memory); // only external methods can be initialized inside the interface methods}contract SolidityTest1 is SolidityTest{ // Here we have inherited the SolidityTest using SolidityTest1function get_String (string memory mrx) public pure returns(string memory){return mrx; }}contract SolidityTest2{SolidityTest obj;constructor(){obj=new SolidityTest1(); }function show_String() public view returns(string memory){return obj.get_String("Mr.Examples"); }}
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To get more understand regarding the working of the Interfaces have a look at the example below:

Example: 

pragma solidity ^0.8.0;interface SolidityTest{ // Here we declare an interface// only external methods can be initialized inside the interface methodsfunction get_Sum(uint mrx,uint ample) external view returns(uint); function get_Product(uint mrx,uint ample) external view returns(uint); function get_Difference(uint mrx,uint ample) external view returns(uint); function get_Modulus(uint mrx,uint ample) external view returns(uint); }contract SolidityTest1 is SolidityTest{ // Here we have created another contract named as SolidityTest1 and have inherited from SolidityTestfunction get_Sum(uint mrx,uint ample) public pure returns(uint){return mrx+ample; }function get_Product(uint mrx,uint ample) public pure returns(uint){return mrx*ample; } function get_Difference(uint mrx,uint ample) public pure returns(uint){return mrx-ample; } function get_Modulus(uint mrx,uint ample) public pure returns(uint){return mrx%ample; } }contract SolidityTest2{SolidityTest mrx_obj; constructor(){mrx_obj=new SolidityTest1();}function obtain_Values() public view returns(uint,uint,uint,uint){return(mrx_obj.get_Sum(2,3),mrx_obj.get_Product(4,6),mrx_obj.get_Difference(7,3),mrx_obj.get_Modulus(6,3)); }}
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Example Explanation

In above example, we define an interface called SolidityTest that includes four function signatures. These functions are declared as external view, meaning that they do not modify the state of the contract and can be called from outside the contract.

We then define a contract called SolidityTest1 that implements the functions from SolidityTest. These implementations use the pure modifier, which indicates that the functions do not read from or modify the contract’s state.

Finally, we define a second contract called SolidityTest2 that creates an instance of SolidityTest1 and uses it to call the get_Sum, get_Product, get_Difference, and get_Modulus functions. These function calls are made using the mrx_obj instance of SolidityTest1, which is stored as a state variable in SolidityTest2.


Benefits of Using interfaces

Solidity interfaces are beneficial for contract development for several reasons:

  • Interfaces allow contracts to interact in a standardized manner. Interfaces provide a consistent and reliable way for contracts to communicate with one another by defining a set of functions.
  • Contracts can be made more flexible and modular by using interfaces. It is possible to design contracts that work together in a plug-and-play manner by utilizing interfaces, which allow developers to swap out one contract implementation for another without affecting the overall system.
  • Interfaces make it possible to decouple contracts from each other. As a result, contracts can be developed and tested independently, which improves overall development efficiency.
  • Interfaces allow contracts and systems to work together. Standard interfaces make it possible for contracts to interact with one another across different platforms and systems, enabling greater connectivity and compatibility.

Conclusion

Solidity interfaces are critical concepts for smart contract development that increase flexibility, standardization, and interoperability. They enable contracts to communicate and interact reliably and consistently, which is essential for developing complex decentralized applications.

Using interfaces, you can create modular, interoperable, and standardized contracts that work seamlessly within a decentralized ecosystem by specifying a set of functions contracts need to perform. Therefore, Solidity interfaces can be used to create smart contracts that are reliable, secure, and scalable.

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