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> While true, if your language doesn’t support such a type You'd be surprised where the support is. In C#, you would declare a struct type with one read only f
by SideburnsOfDoom 6y ago
> While true, if your language doesn’t support such a type
You'd be surprised where the support is. In C#, you would declare a struct type with one read only field of type double, and range validation (x <= x <= 1) in the constructor.
this is the "value object" pattern. http://wiki.c2.com/?ValueObject http://wiki.c2.com/?ValueObject
Yes there's a bit of boilerplate - especially since you might want to override equality, cast operators etc. But there is support. And with a struct, not much overhead to it.
- kaoD 6y agoI don't think runtime validation is that special. You can bend most languages into this pattern one way or another. The real deal is having an actual compile-time-checked type that resembles a primitive.
- SideburnsOfDoom 6y agoActually what I want is just the reading experience of seeing "public Customer GetById(CustomerId id)" instead of "public Customer GetById(string id)" when only some strings (e.g. 64 chars A-Z and 1-9) are valid customer ids. Compile-time validation would be ideal, but validation at the edges, well before that method, is good enough.
- SideburnsOfDoom 6y agoSee: "Primitive Obsession" https://wiki.c2.com/?PrimitiveObsession https://wiki.c2.com/?PrimitiveObsession Usually cured by using Value objects. I wish this done more in OO code. Could it be better supported in these languages? Yes, for sure. But is it true that "these language do not support such a type" at all? No.