Ethscriptions Virtual Machine Docs

Error Handling

Rubidity provides a set of tools to help you write secure and reliable smart contracts. This includes native support for preconditions via require statements and automatic type checking for variables and parameters.

Require Statements

The require function is used to ensure that certain conditions are met before a function proceeds. If the condition specified in require is false, the function will throw an error, and all changes to the state will be reverted.
Here's an example that demonstrates the use of require in a mint function:
function :mint, { amount: :uint256 }, :public do
# Ensure the mint amount is positive
require(amount > 0, 'Amount must be positive')
# Ensure the mint amount does not exceed a pre-defined per mint limit
require(amount <= s.perMintLimit, 'Exceeded mint limit')
# Ensure the total supply won't exceed the max supply
require(s.totalSupply + amount <= s.maxSupply, 'Exceeded max supply')
# Proceed to mint
_mint(to: msg.sender, amount: amount)
In this example, the require statements act as guards that prevent undesirable actions. If any of the require statements fail, the function will terminate, providing the string message as an error reason.

Type Checking

Rubidity also performs automatic type checking on function parameters and state variables. This means that if you declare a variable as a :uint256, Rubidity will ensure that you can only assign unsigned 256-bit integers to that variable. Any attempt to assign a different type will result in a runtime error.