# 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:

```ruby
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`:

```ruby
string :public, :name
```

Declare a public unsigned integer named `totalSupply`:

```ruby
uint256 :public, :totalSupply
```

### Advanced Types

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

#### **Mappings**

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

#### **Arrays**

```ruby
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:

```ruby
s.variable_name
```

Example:

```ruby
# 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.

***

<br>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.ethscriptions.com/ethscriptions-vm/rubidity/state-variables.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.