Limiting the time (time/date based) that a contract method can be called

Question

I'd like to publish a contract that allows calls up until a certain time and date.

For example, say I want to allow anyone to call it for 1 year after publishing the contract to the blockchain, then after that time I want that method to no longer work when called.

How might this be implemented, ideally using a Smartpy example?

Answer 1

You can do this by simply adding a time check.

import smartpy as sp

class TimedCall(sp.Contract):
    def __init__(self):
        self.init(
            time_limit = sp.timestamp_from_utc_now().add_days(365),
            val = sp.nat(5)
        )
    
    @sp.entry_point
    def timed_method(self, param):
        sp.set_type(param, sp.TNat)
        
        sp.verify(sp.now < self.data.time_limit, "TIME LIMIT CROSSED")
        
        self.data.val = param

@sp.add_test(name = "main")
def test():
    scenario = sp.test_scenario()
    
    c = TimedCall()
    
    scenario += c
    
    current_time = sp.timestamp_from_utc_now()
    
    # PASSED call
    scenario += c.timed_method(6).run(now = current_time.add_days(50))
    
    # FAILED call
    scenario += c.timed_method(7).run(now = current_time.add_days(366), valid = False)

IDE link: https://smartpy.io/ide?cid=QmVrHP4qpWbDwXd2MsYPEsCnZGhz7naVSHPKwG4NdJGHSU&k=05862a678a886954120c