This is an important bug fix that corrects aliasing. As reported in #32 , operations such as:
dual a = 1;
a = a - 2*a;did not work as expected, because a is used on the right-hand side expression. As this expression is evaluated, a changes and so does the other occurrences of a in the expression.
To prevent this, the default behavior needs to be such that the result of the expression is stored in a temporary, and then the self dual object is assigned to this temporary.
In a future release, something similar to Eigen .noalias() method could be envisioned if the user is sure there is no alias on the right-hand side expression.