Common Smart Contract Functions

is_account

Declaration:

def is_account(account: Name ) -> bool:
    ...

Explanation:

Used to determine if an account exists.

has_auth

Declaration:

def has_auth(account: Name) -> bool:
    ...

Explanation:

Used to determine if the 'active' permission of the specified account is present, i.e. whether the Transaction is signed with the private key corresponding to the 'active' permission of the specified account. There is at least one corresponding private key, and possibly multiple.

require_auth/require_auth2

Declaration:

def require_auth(account: Name):
    ...

def require_auth2(account: Name, permission: Name):
    ...

Explanation:

Both of these functions throw an exception when the account does not exist or the specified account's permission is not detected. The difference is that require_auth checks for the existence of the 'active' permission, while require_auth2 can check for a specified permission.

publication_time/current_time

check

Declaration:

def check(test: bool, msg: str) -> None:

Explanation:

If test is False, an exception will be thrown. This function is frequently used in smart contracts, and can be referenced in the code of token.codon.

Example Code:

from chain.action import has_auth, require_auth, require_auth2, is_account
from chain.contract import Contract

@contract(main=True)
class MyContract(Contract):

    def __init__(self):
        super().__init__()

    @action('test')
    def test(self):
        has_auth(n"hello")

        require_auth(n"hello")
        require_auth2(n"hello", n"active")

        print(is_account(n"hello"))
        print(is_account(n"hello"))
        return

Compilation:

python-contract build common_example.codon

Test code:

def test_common():
    t = init_test('common_example')
    ret = t.push_action('hello', 'test', {}, {'hello': 'active'})
    t.produce_block()
    logger.info("++++++++++%s\n", ret['elapsed'])

Test:

ipyeos -m pytest -s -x test.py -k test_common

Output:

[(hello,test)->hello]: CONSOLE OUTPUT BEGIN =====================
True
True

[(hello,test)->hello]: CONSOLE OUTPUT END   =====================