Find values for $a$ and $b$ so that $f\left(x\right)$ will be continuous for all values of $x$. 

$f\left(x\right)=\left\{ \begin{array}{ll1} 2x+a & \mbox{for $x \leq -2$}\\ x^2-2 & \mbox{for $-2<x \leq 3$}\\ -x+b & \mbox{for $x>3 $}\end{array} \right.$