I am trying to convert my solidity code into vyper but I can't find a way to declare a storage variable.

My solidity function was this:

struct Account {
uint256 balance; // Account's balance
uint256 timeLocked; // If not 0, then account will be allowed to withdraw 
mapping (address => Account) public accounts;

function addBalance() public payable {
Account storage a = accounts[msg.sender];
a.balance = a.balance + msg.value;


How can I make ato become a storage variable ?

I have another question, how can I make a require statement like this ?

require(_operator != address(0));

Seems that address(0) doesn't exist in vyper as it throws me errors.

1 Answer 1


Can't you just bypass the use of a completely?

struct Account:
    accountBalance: wei_value
    timeLocked: uint256

accounts: public(map(address, Account))

def addBalance():
    self.accounts[msg.sender].accountBalance += msg.value

Note that balance is a reserved keyword, so I've used accountBalance.

Seems that address(0) doesn't exist in vyper as it throws me errors.


assert _operator != ZERO_ADDRESS

ZERO_ADDRESS is a built-in constant.

  • Actually I use a to emit an event emit Balance(msg.sender, a.balance); Jun 4, 2019 at 13:59
  • Thanks for answering my question, there isn't a lot of documentation out there Jun 4, 2019 at 14:31
  • Just poking around at Vyper examples, it doesn't look like storage or memory pointers are implemented, so I think you might have to use self.accounts[msg.sender] explicitly in your event call: log.Balance(msg.sender, self.accounts[msg.sender].accountBalance). Jun 4, 2019 at 14:38
  • That worked, thanks! Do you know how to declare a getter function, I've tried like this def getBalance() -> uint256(wei): but it creates a setter function instead Jun 4, 2019 at 19:46
  • Glad it worked :-) Getter functions can be created implicitly (as they are in Solidity) by using the public() function. So when we declared the mapping, you'll notice it was wrapped in a public() call. This means the getter function should be automagically created, and so you don't need to explicitly create one. Jun 4, 2019 at 19:53

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