Immutable variables are like constants except values are assigned when the contract is deployed.
When to use immutable variables?
- You have a variable that needs to be set when the contract is deployed. For example, setting contract owner to
msg.sender. - And this variable will never change after deployment.
Why declare variables as immutable?
- Like constants,
immutable variables save run time gas
# pragma version ^0.4.0
OWNER: public(immutable(address))
MY_IMMUTABLE: public(immutable(uint256))
@deploy
def __init__(val: uint256):
OWNER = msg.sender
MY_IMMUTABLE = val
@external
@view
def get_my_immutable() -> uint256:
return MY_IMMUTABLE
