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Lesson 23:
Payable
Introduction to payable keyword and how to use it in your smart contracts.
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Payable
The payable keyword in Solidity is used to indicate that a function can receive Ether. This is required if you want to receive Ether in a function.
An exception will be thrown if the receiving contract does not have a receive function receive() external payable {...}.
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
contract PayableExample {
// Payable address can receive Ether
address payable public recipient;
// Payable constructor can receive Ether
constructor(address payable _recipient) {
recipient = _recipient;
}
// Function to deposit Ether into this contract.
// Call this function along with some Ether.
function deposit() public payable {}
// Function to withdraw all Ether from this contract.
// Notice how this function below does not need payable keyword.
// It has been defined in the global recipient variable.
function withdraw() public {
// get the amount of Ether stored in this contract
uint256 amount = address(this).balance;
// send all Ether to recipient
(bool success,) = recipient.call{value: amount}("");
require(success, "Failed to send Ether");
}
// Function to transfer Ether from this contract to another address
function transfer(address payable _to, uint256 _amount) public {
// Note that "_to" is declared as payable
(bool success,) = _to.call{value: _amount}("");
require(success, "Failed to send Ether");
}
// This function is called when Ether is sent without data
receive() external payable {
deposit();
}
}