3 ms·

Most of the time `const` is only needed for the caller to ensure that the object won't get changed when passed to another function. In addition, to enforce imm

Most of the time `const` is only needed for the caller to ensure that the object won't get changed when passed to another function. In addition, to enforce immutability in C++, you have to disable copy/move constructors and assignment operators, which removes much benefit of using values instead of references.

seabee 12y ago
I see this sometimes in code at work. As soon as you need to stuff one of the 'const' objects into any kind of container you start requiring unique_ptrs everywhere, and then you start thinking how much easier your life would be if you wrote Haskell for a living instead.
coliveira 12y ago
> `const` is only needed for the caller to ensure that the object won't get changed when passed to another function. But const cannot guarantee this, because it can be cast away so easily. This could be true just for your own code, but then it is you who is responsible for maintaining the immutability, not the compiler.
- netheril96 12y ago
  > because it can be cast away so easily By this logic, none of the static type checks in C++ is of any use, since they can be cast away easily as well.
  - mlvljr 12y ago
    Involving an UB (unlike const_cast)! :)
  - coliveira 12y ago
    Types exist to help you organize your code. Const (for classes) just promotes the misguided idea that you should design objects with mutable and immutable parts at the same time. The main objection to this is that your objects should be either value objects (therefore immutable) or reference objects. There is no need for const if you design your classes in this way. On the other hand, the const idea requires you to spread "const" everywhere you might want immutability, otherwise the compiler will fight you at each line of your code. Either way, it is a loss-loss proposition.

3 ms·

Most of the time `const` is only needed for the caller to ensure that the object won't get changed when passed to another function. In addition, to enforce imm

by netheril96 12y ago

seabee 12y ago
I see this sometimes in code at work. As soon as you need to stuff one of the 'const' objects into any kind of container you start requiring unique_ptrs everywhere, and then you start thinking how much easier your life would be if you wrote Haskell for a living instead.
coliveira 12y ago
> `const` is only needed for the caller to ensure that the object won't get changed when passed to another function. But const cannot guarantee this, because it can be cast away so easily. This could be true just for your own code, but then it is you who is responsible for maintaining the immutability, not the compiler.
- netheril96 12y ago
  > because it can be cast away so easily By this logic, none of the static type checks in C++ is of any use, since they can be cast away easily as well.
  - mlvljr 12y ago
    Involving an UB (unlike const_cast)! :)
  - coliveira 12y ago
    Types exist to help you organize your code. Const (for classes) just promotes the misguided idea that you should design objects with mutable and immutable parts at the same time. The main objection to this is that your objects should be either value objects (therefore immutable) or reference objects. There is no need for const if you design your classes in this way. On the other hand, the const idea requires you to spread "const" everywhere you might want immutability, otherwise the compiler will fight you at each line of your code. Either way, it is a loss-loss proposition.