RigidbodyConstraints2D overwrites previous RigidbodyConstraints2D

Questions & Answers
1

Why is it that in Rigidbody2D, RigidbodyConstraints2D overwrites previous RigidbodyConstraints2D. Im trying to lock Constraints on freeze postion y and freeze rotation z with code.

t.GetComponent<Rigidbody2D> ().constraints = RigidbodyConstraints2D.FreezeRotation;  
t.GetComponent<Rigidbody2D> ().constraints = RigidbodyConstraints2D.FreezePositionY;
2

By default this is set to RigidbodyConstraints.None, allowing rotation and movement along all axes. In some cases, you may want to constrain a Rigidbody to only move or rotate along some axes, for example when developing 2D games. You can use the bitwise OR operator to combine multiple constraints.

http://docs.unity3d.com/ScriptReference/Rigidbody-constraints.html

GetComponent<Rigidbody2D> ().constraints = 
			RigidbodyConstraints2D.FreezeRotation | 
			RigidbodyConstraints2D.FreezePositionY;