Secure Treasure Chest
10 Points
opaque-types
Instructions
Sharp eyed students will have noticed that the TreasureChest type in the previous exercise wasn't that secure!
If you used the get_treasure function you had to supply the password, but you could still destructure the TreasureChest type to get the treasure without having to know the password.
Let's fix that by using an Opaque Type.
1. Define the TreasureChest opaque type.
The TreasureChest contains two fields:
- A password that is a
String. - A treasure that is a generic type.
The TreasureChest type must be opaque.
2. Define the create function.
This function takes two arguments:
- A password
String. - A treasure value of any type.
The function returns a TreasureChest containing the password and the value.
If the password is shorter than 8 characters then the function should return an error saying Password must be at least 8 characters long.
3. Define open function.
This function takes two arguments:
- A
TreasureChest. - A password
String.
If the password matches the password in the TreasureChest then the function should return the treasure, otherwise it should return an error saying Incorrect password.
Secure Treasure Chest
10 Points
opaque-types
Instructions
Sharp eyed students will have noticed that the TreasureChest type in the previous exercise wasn't that secure!
If you used the get_treasure function you had to supply the password, but you could still destructure the TreasureChest type to get the treasure without having to know the password.
Let's fix that by using an Opaque Type.
1. Define the TreasureChest opaque type.
The TreasureChest contains two fields:
- A password that is a
String. - A treasure that is a generic type.
The TreasureChest type must be opaque.
2. Define the create function.
This function takes two arguments:
- A password
String. - A treasure value of any type.
The function returns a TreasureChest containing the password and the value.
If the password is shorter than 8 characters then the function should return an error saying Password must be at least 8 characters long.
3. Define open function.
This function takes two arguments:
- A
TreasureChest. - A password
String.
If the password matches the password in the TreasureChest then the function should return the treasure, otherwise it should return an error saying Incorrect password.