Raising exceptions

Once an exception is raised, it cannot be caught.

Error messages may take a lot of space in smart contracts.

Exceptions cannot be caught, the whole operation is backtracked if an exception occurs.

sp.failwith aborts the current transaction and raises a message of arbitrary type.

python

@sp.entrypoint
def ep(self):
    sp.if self.data.x > 10:
        sp.failwith("x is bigger than 10")

Besides sp.failwith, sp.verify and sp.verify_equal, exceptions can also be raised by other constructions:

Accessing fields my_map[x]
The exception raised is a pair containing the (x, my_map).
Opening variants .open_some(<message>)
This may fail with sp.unit.
Dividing by zero 1 / 0
Variable step in a range which is 0 sp.for i in sp.range(1, 10, step = 0)

Raising exceptions ​