alt Hacker NewsPutting code with side effects into an assert is asking for trouble. Compile with NDEBUG set and the effects mysteriously disappear! Anything beyond an equality expression or straight boolean should be avoided.
Replies
Indeed.
bool is_even(int* valPtr) {
assert(valPtr != nullptr);
return *valPtr % 2;
}
[0] https://dev.epicgames.com/documentation/en-us/unreal-engine/...
That's why you define your own assert macro and keep in on unconditionally. Your programs will be better for it.
This is just a symptom of a bad assert() implementation, which funny enough is the standard. If you properly (void) it out, side effects are maintained.
https://github.com/fiberfs/fiberfs/blob/7e79eaabbb180b0f1a79...
Side effects are bad of course, but anything beyond a straight boolean or equality is bad?
`assert(vector.size() < 3)` is ridiculous to you?
I don't mean to be that guy, but for "functional" programmers a print statement has "side effects".
But your meaning is clear. In an assert expression, don't call functions that might change the program/database state. Be as "const" as possible.
I once spent several days debugging that same mistake. Stuff worked perfectly in tests but broke misteriously in production builds. Couldn't stop laughing for a few minutes when I finally figured it out.