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How to code smart contracts

Ever since they were introduced by Ethereum, smart contracts have played a key role in expanding the Web3 ecosystem. They enabled Ethereum to become a platform for decentralized applications and inspire a host of challengers with sharpened focus on smart contract development.

If you pursue a career as a Web3 developer, chances are that at some point you’ll be involved in smart contract development, so it’s important to have an idea of what to expect. In this article, we examine some of the most important things you need to know about smart contract coding.

What are smart contracts?

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Smart contracts are self-executing programs that run on a blockchain network and are designed to execute certain operations when certain conditions are met. For example, an ERC-20 token contract on Ethereum may be programmed to ‘mint’ a new type of crypto asset when it receives a specified amount of ETH.

Ethereum was the first network with smart contract capabilities, made possible thanks to the Ethereum Virtual Machine. The Ethereum Virtual Machine has been so influential that other prominent Web3 protocols like Binance Smart Chain and Hedera Hashgraph have built their own EVM implementations to be able to support Ethereum smart contracts.

How to code smart contracts

On the surface, smart contract coding has a lot in common with conventional software development, but there are a lot of specifics that you need to take into account. Let’s start with the basics.

First, you’ll need to choose a language for writing smart contracts. Solidity is most commonly associated with smart contract development because it is natively supported by Ethereum. However, you have other viable alternatives like Vyper and Yul, each of them having their distinct advantages and disadvantages. You can even write smart contracts in Rust, which is one of the most popular languages for software development.

Next, you’ll need reliable tools to help you code smart contracts efficiently and securely. There is an abundance of great tools and resources out there, especially when it comes to Ethereum, which is by far the most popular platform that supports smart contacts. These include popular development environments and frameworks like Hardhat and Truffle, the development kit Foundry, the popular libraries OpenZeppelin and Ethers.js and others.

The quirks of smart contract development

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While smart contract development is similar to conventional programming in a lot of ways, it has its own requirements and constraints that every Web3 dev needs to take into account. For example, the size of Ethereum smart contracts is limited to 24KB to ensure that they do not run out of gas. This limitation can be circumvented with the help of the Diamond Pattern, which allows devs to create modular smart contract systems that can be extended after they’ve been deployed on Ethereum.

Similarly, smart contract upgradability is not natively supported on Ethereum, but it can be achieved using third-party solutions, such as OpenZeppelin’s method for upgradable contracts. Meanwhile, some Web3 protocols, for example Flow, are designed to support contract upgradability natively.

Also noteworthy is the fact that smart contracts cannot get information from off-chain sources. This is done in order to ensure that the blockchain remains entirely deterministic. So in order to utilize off-chain data in their contracts, devs leverage special entities called oracles, which function as a bridge between the blockchain and the real world. An oracle’s role is to retrieve data from verified off-chain sources and submit that information to the blockchain in a form that can be used in smart contracts.

Gas consumption

One of the pitfalls of smart contract development stems from the fact that every interaction on Ethereum costs gas, which is essentially the fee for using the network to process transactions and store information. So you can make a smart contract that is way too costly to execute. This is why gas cost optimization is a crucial consideration when coding smart contracts.

Contract composability

Keep in mind that you can have multiple smart contracts working together to build powerful applications and create novel use cases. Smart contracts on public blockchains like Ethereum are accessible to anyone on the network, so you can call an existing contract in your own smart contract. You can even have smart contracts that deploy other contracts.

Good practices for smart contract development

There are a number of good development practices that will help you to code better smart contracts. Let’s go through some key smart contract development principles.

What’s your goal?

You need to have a clear vision of what you want to achieve with a particular smart contract. This will help you to identify where it fits within the broader architecture of a dApp and allow you to be more efficient during the subsequent development process.

Keep it simple

Simple is better when it comes to smart contract development. Try to use clear and concise code as much as possible. This will lessen the risk of errors. Also, where possible, use already written code that’s well tried and tested.

Have a plan to avoid failure

Smart contract development is a complicated discipline, so mistakes are a common occurrence. What’s important is to have a plan for addressing such mistakes. The good news is that there are a number of techniques that can help you mitigate the impact of bugs and errors. Using circuit breakers to pause the contract and limiting the money that would be at risk are some of the measures you can implement to prevent a significant failure. Also, you can utilize upgradable contracts to implement fixes.

Optimize your smart contract code

Always look for ways to optimize your code for gas consumption. 


Rigorous testing is your best weapon against bugs and glitches. In addition, make sure that your smart contract code has been reviewed by a top-tier external auditor.

The journey begins

As with everything, the first steps into smart contract coding are bound to be hesitant, but the pace inevitably steadies as expertise grows. Hard work, dedication and a desire to learn and improve are the keys to becoming a world-class smart contract developer, none of them out of reach.

Learn more about “What are blockchain nodes” and “Road to Web3

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Researched and written by

Savina Todorova
Marketing @LimeAcademy

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