C++, LHS state after exception is thrown

Question

hi. I am learning C++ exceptions and I would like some clarification of the scenario:

T function() throw(std::exception);
...
T t = value;
try { t = function(); }
catch (...) {}

if the exception is thrown, what is the state of variable t? unchanged or undefined?

Answer 1

t is not set because the exception is thrown before the assignment. The function would have to return a value for t to be set.

Answer 2

Unchanged. t can't be assigned until function() returns a value, and function() never returns normally

Answer 3

It is not that simple. Your catch clause will also catch exceptions raised by the assignment operator for the t object class. The t object might be partially assigned. Never catch all exceptions and assume that the most likely thing happened.