Why can't structs be declared as const?

Question

They are immutable value types on the stack. What keeps me from having them a const?

References:

• http://msdn.microsoft.com/en-us/library/ah19swz4(v=vs.71).aspx
• http://msdn.microsoft.com/en-us/library/aa664465(v=vs.71).aspx
• http://msdn.microsoft.com/en-us/library/aa288471(v=vs.71).aspx

Answer 1

Because the value type constructor might do anything -- for example, switch logic based on the time of day. Constant value types makes sense intellectually, but it simply cannot work on custom value types in practice due to the flexibility of constructors to do whatever they please. (Remember that constants are evaluated at compile time, which means your constructor would have to be run at compile time.)