To understand what low-level calls in solidity are, we must first define solidity and understand its applications. Solidity is a programming language inspired by Python, C++, and JavaScript that is used to create smart contracts for the Ethereum virtual engine.
Smart contracts are self-executing contracts in which the conditions of the buyer-seller agreement are inscribed into lines of code.
In this post, we will look at the principles of solidity low-level calls, how they function, and how they can be used to create smart contracts.
What are Low-Level calls in Solidity?
Solidity's low-level calls enable smart contracts to interface with other contracts or accounts on the Ethereum network.
Low-level calls offer a lower-level interface to the EVM than the Solidity language does, allowing developers to create more complicated and optimized smart contracts.
Low-level calls may be used to invoke any function in any Ethereum contract or account, not simply those written in Solidity.
The only prerequisites are that the function is callable from the Ethereum Virtual Machine and have a public or external visibility modifier (EVM).
Types of Low-Level Calls in Solidity
Solidity supports four forms of low-level calls: call, delegatecall, staticcall, and send. Each of these functions has its own set of capabilities and applications.
Call
In Solidity, the call function is the most fundamental type of low-level call, and it is used to invoke a function in an external contract or account.
The call function accepts a bytes memory argument containing the data to be sent to the external contract or account.
In addition, the call function returns a boolean value indicating whether or not the function call was successful.
If the call was successful, the function returns true, and the data returned by the external contract or account is put in the calling contract's memory.
If the call was unsuccessful, the function returns false and the calling contract's memory remains intact.
The call function has the following signature:
(bool success, bytes memory data) = address.call(bytes memory data);
Delegatecall
In Solidity, the delegatecall function is similar to the call function, but it has a distinct purpose.
The delegatecall function is used to call a function in an external contract while preserving the context of the calling contract.
This implies the external contract uses the same storage, contract address, and contract balance as the calling contract.
The delegatecall function can be useful for building upgradeable contracts, in which the contract's code can be modified without impacting the contract's storage.
The delegatecall function has the following signature:
(bool success, bytes memory data) = address.delegatecall(bytes memory data);
Staticcall
In Solidity, the staticcall function is used to call a function in an external contract, but it does not enable the external contract to change the state of the calling contract.
The staticcall function is helpful for reading data from an external contract while keeping the caller contract's state constant.
The staticcall function additionally provides a boolean value indicating whether or not the function call was successful, as well as the external contract's return data.
The staticcall function has the following signature:
(bool success, bytes memory data) = address.staticcall(bytes memory data);
Send
In Solidity, the send function is used to transfer ether to an external contract or account.
The send function may be used to transfer small amounts of ether to other contracts or accounts, although it has some limits.
The send function only offers a 2300 gas stipend, making it unsuitable for contacting functions in external contracts that demand a high quantity of gas. Moreover, the send function returns no data from the external contract or account.
The send function has the following signature:
bool success = address.send(uint256 amount);
Using Low-Level Calls in Solidity
In Solidity, low-level calls can be used in a number of ways. Among the most prevalent use cases are:
Contract Interactions
Low-level calls are widely used in contract interactions, such as calling functions in external contracts or accounts.
A smart contract, for example, may utilize a low-level call to send a payment to another contract or to receive data from an external contract.
Upgradability
Upgradability in smart contracts may be implemented via low-level calls. A smart contract can call a function in another contract while keeping its own context by utilizing the delegatecall function.
This can be beneficial for building upgradeable smart contracts, in which the contract's code can be altered without impacting the contract's storage.
Gas Optimization
Low-level calls can be utilized in smart contracts to optimize gas use. A smart contract can read data from another contract without affecting its own state by utilizing the staticcall function.
This can help lower the quantity of gas utilized by the smart contract and increase its efficiency.
Conclusion
Low-level calls are a feature of Solidity that allows smart contracts to interface with other contracts and accounts on the Ethereum network.
Low-level calls offer a lower-level interface to the EVM than the Solidity language does, allowing developers to create more complicated and optimized smart contracts.
In Solidity, there are four types of low-level calls: call, delegatecall, staticcall, and send, each with its own set of capabilities and use cases.
Low-level calls, among other things, can be utilized for contract interactions, upgradability, and gas optimization.