Variables

Variable are objects containing information which can be referenced or manipulated throughout your code. Variables must be declared with data types.

There are 4 types of variables in Vyper:

State Variables
- Declared outside of functions
- Stored on the blockchain
Local Variables
- Declared inside functions
- Not stored on the blockchain
Global Variables
- Provides information about the blockchain
self Variable
- Naming convention which read and write to state variables
- Call internal functions within the contract

# pragma version 0.4.0

# State variables
SUPPLY_AMOUNT: uint256
BYTES_VALUE: constant(bytes32) = 0xabcd1123f8ae9a65dcc16f95643f2030aa505c6b465c8206e26ae84b525cdacb
STRING_VALUE: constant(String[13]) = "Hello, world!"

@external
@view
def retrieve_local_variable() -> (uint256):

    # Local Variables
    data: (uint256) = 123456
    return data

@external
@view
def retrieve_global_variables() -> (address, uint256, bytes32):
    block_coinbase: address = block.coinbase
    block_difficulty: uint256 = block.difficulty
    block_prevrandao: bytes32 = block.prevrandao
    return (block_coinbase, block_difficulty, block_prevrandao)

@external
def set_self_variable():
    self.SUPPLY_AMOUNT = 999

@external
@view
def view_self_variable() -> (uint256):
    return self.SUPPLY_AMOUNT

Vyper Differentiators

Vyper has an additional self variable similar to Python used to refer to the contract itself.

Variables

Further Reading: