How to child a control point of a Bezier curve to an object The straight line is a 2D Bezier curve, with two control points. The bevel function gave it some thickness. The circle is a separate 2D object.

Now, when the circle moves, the idea is that that end of the Bezier curve should move with the circle, staying at the circle's center. The other end should remain where it is.

So, somehow that end of the Bezier curve should be "attached" to the center of the circle. I thought using the Hook modifier. But that requires a vertex group to attach to the object. Bezier curves apparently can't have vertex groups (couldn't find it in the property view), so can't use the modifier. Then I considered using the parent function, but apparently a vertex can indeed parent an object, but an object cannot parent a vertex (at least, I couldn't find a way). And anyway, again, Bezier curves don't have vertices. So wouldn't have worked either.

Anyone?
I found the solution in a YouTube video:

Suppose you want to make Object A the parent of a control point in a Bezier curve (Object B).


select Object A, then shift-select Object B (so both objects are selected)
click edit mode. Object B will open edit mode.
select the control point you want to "attach" to Object A. click ctrl+H. 
choose "selected object"


When you now move Object A, the control point will move accordingly, while the other control points of Object B won't, hence deforming the Bezier curve.

PS: you can also use this method when Object B is a simple mesh object (i.e. vertices instead of control points).