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Ethereum: Solidity Basics
As a developer building blockchain applications, it is very important to understand the basics of Solidity. In this article, we will dive into the basics of Solidity, the programming language used for Ethereum smart contracts.
What is Solidity?
Solidity is a programming language specifically designed for writing smart contracts on the Ethereum blockchain. It is an open-source language based on C++ with some additional features and constructs designed for blockchain development.
Solidity Basics
Before we dive into specific topics, let’s cover some basics:
- Variables: Variables are used to store data in a contract.
- Functions
: Functions are reusable blocks of code that perform a specific task. In Ethereum contracts, functions are elements of complex logic.
- Events: Events are triggered by specific actions in a contract and can be used to notify other parties about changes in the state of the contract.
Basic Solidity Syntax
Here is an example of basic Solidity syntax:
pragma robustness ^0.6.0;
contract MyContract {
public uint myVariable;
function claimAssetsFromBridge(
bytes callData message,
bytes callData validation
) public {
// Comment: This is a Solidity comment, not code.
// Use the "function" keyword to write code and define variables or functions here.
}
}
In this example:
pragma solidity ^0.6.0;is a pragma directive that specifies the version of Solidity to use.
contract MyContract {... }defines the scope of the contract.
- public uint myVariable; declares and initializes a variable of type uint.
- “Function ClaimAssetsFromBridge(ByteCallDataMessage, ByteCallDataAttestation)” is an event function that accepts the parameters “message” and “attestation”.
Variables
Solidity variables are declared using the “var” keyword:
pragma robustness ^0.6.0;
contract MyContract {
public uint myVariable;
public constructor () {
// Comment: This is a Solidity comment, not code.
// Use the "constructor" keyword to write the code.
myVariable = 10; // Initialize the variable with the initial value
}
}
Variables can be declared inside a function, class, or module.
Features
Robustness functions are defined using the “function” keyword:
pragma robustness ^0.6.0;
contract MyContract {
public uint myVariable;
function claimAssetsFromBridge(
bytes callDataMessage,
bytes callDataValidation
) public {
// Comment: This is a Solidity comment, not code.
// Use the "function" keyword to write code and define variables or functions here.
myVariable = 20; //Updates the value of the variable
}
}
Functions can accept any type of input parameters, including “bytes”, “uint”, “address”, etc.
Events
Solidity events are triggered by specific actions in a contract. Events can be used to notify other parties about changes in the state of the contract:
pragma robustness ^0.6.0;
contract MyContract {
public uint myVariable;
event ClaimedAssetsFromBridge(
addressIndexed sender,
uint256 sumRequired
);
function claimAssetsFromBridge(
messageByteCallData,
validationByteCallData
) public {
// Comment: This is a Solidity comment, not code.
// Use the "event" keyword to write your code and define the event here.
emit ClaimedAssetsFromBridge(messageSender, 10); // Trigger the event with a notification
}
}
Events can be passed using the “release” keyword.