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#pragma once
///@file
#include <cassert>
#include <exception>
/**
* A trivial class to run a function at the end of a scope.
*/
template<typename Fn>
class Finally
{
private:
Fn fun;
bool movedFrom = false;
public:
Finally(Fn fun) : fun(std::move(fun)) { }
// Copying Finallys is definitely not a good idea and will cause them to be
// called twice.
Finally(Finally &other) = delete;
Finally(Finally &&other) : fun(std::move(other.fun)) {
other.movedFrom = true;
}
~Finally() noexcept(noexcept(fun()))
{
try {
if (!movedFrom)
fun();
} catch (...) {
// finally may only throw an exception if exception handling is not already
// in progress. if handling *is* in progress we have to return cleanly here
// but are still prohibited from doing so since eating the exception would,
// in almost all cases, mess up error handling even more. the only good way
// to handle this is to abort entirely and leave a message, so we'll assert
// (and rethrow anyway, just as a defense against possible NASSERT builds.)
if (std::uncaught_exceptions()) {
assert(false &&
"Finally function threw an exception during exception handling. "
"this is not what you want, please use some other methods (like "
"std::promise or async) instead.");
}
throw;
}
}
};
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