@c65b183b @c39d2605 @4c603b88 @462ebf4c Do you have access to change the implementation of (X)? If so, could you define a as a parameter object? In that case, you could at least change the value of a for all of its references in the dynamic scope of (Y). 

 @e5b72764 @4c603b88 @c39d2605 @462ebf4c (X) is read-only