state-variables.md

State Variables

Defining State Variables in Rubidity

Overview

State variables are data elements that store the contract's state. In Rubidity, you can define state variables, specify their types, and set visibility options (public, private, or internal) along with additional flags like immutable and constant.

Basic Syntax

The basic syntax to define a state variable is as follows:

type :visibility, :variable_name, :flags

• type: The type of the variable (uint256, string, etc.)
• visibility: Visibility of the variable (public, private, or internal)
• variable_name: The name of the state variable
• flags: Additional flags like :immutable or :constant

Examples

Declare a public string variable named name:

string :public, :name

Declare a public unsigned integer named totalSupply:

uint256 :public, :totalSupply

Advanced Types

For complex types like mappings and arrays, special syntax is used:

Mappings

mapping ({ key_type: :value_type }), :visibility, :variable_name

Arrays

array :value_type, :visibility, :variable_name

Automatically Generated Getters

Much like Solidity, for every public state variable, Rubidity automatically generates a getter function.

Accessing State Variables in Contract Logic

In your contract logic, you can access state variables using the s object:

s.variable_name

Example:

# Accessing a state variable
function :get_balance, { addr: :address }, :public, :view, returns: :uint256 do
  return s.balances[addr] # Accessing s.balances
end

Flags (Not Yet Implemented)

• :immutable: The variable can only be set once, typically in the constructor.
• :constant: The variable's value is set at compile time and cannot be changed.

---

\