assert( cond, [message] )
- Causes a runtime error if a conditional expression is false.
- cond
-
- The conditional expression to assert.
- message
-
- A message to print when the assertion fails.
You use assert() to confirm that your program is behaving as you expect it to at a specific point in the code. If the conditional expression evaluates to false, assert() triggers a runtime error, and Pico-8 stops the program and reports the error and line number of the assert.
As of Pico-8 v0.1.11, assert() can take an optional message that replaces the default message "assertion failed".
Caution: As of Pico-8 v0.1.6, a runtime error in a coroutine aborts the coroutine but does not report the error. See coresume().
Examples
function divide(num, denom)
assert(denom != 0, 'cannot divide by zero')
return num/denom
end
print(divide(12, 4)) -- 3
print(divide(7, 0)) -- runtime error, assertion failed