Assert
Cairo's Assert statements can be used for 2 different use cases:
- Check if two variables are the same
- Set a variable's value if it's currently not set
Note that the usage of assert
can feel unintuitive at times as asserts also set values rather than just checking the value of it.
Example
func main():
tempvar a = 1
tempvar b
# Check if `a` is set to `1`.
assert a = 1
# One might assume that this checks if `b` is set to `1`.
# However given that `b` is not set yet, it'll be set to
# `1` via this `assert` usage.
assert b = 1
# Check if `b` is set to `2` which will fail.
assert b = 2
return ()
end