CODEWITHSUNDEEP
c#interfacecode-contracts
gt.guybrush
gt.guybrush

Reputation: 1378

Code Contract on property in Interface

Hi iam trying to put my code contract on interface on my class and i write something like this:

[ContractClass(typeof(MyClassContract))]
interface IMyClass
{
    int Id { get; set; }
}

[ContractClassFor(typeof(IMyClass))]
sealed class MyClassContract : IMyClass
{
    public int Id
    {
        get { return Id; }
        set { Contract.Requires(value > 0); }
    }
}

public class MyClass : IMyClass
{
    private int _id;
    public int Id
    {
        get { return _id; }
        set { _id = value; }
    }

}

but don't like to be forced to define a get in contract that will be never used, mean that i can write it as

get { return "abcdrdkldbfldsk"; }

and don't like to be forced to use public property in an internal class only because cant write 

get { return ImyClass.Id; }

EDIT: this is what i would like to write:

[ContractClassFor(typeof(IMyClass))]
sealed class MyClassContract : IMyClass
{
    int IMyClass.Id
    {
        set { Contract.Requires(value > 0); }
    }
}

Upvotes: 1

Views: 1216

Answers (1)

StuartLC
StuartLC

Reputation: 107267

If you add a Contract invariant in the ContractClassFor (MyClassContract):

[ContractInvariantMethod]
private void ObjectInvariant ()
{
  Contract.Invariant (Id >= 0);
}

Then an Ensures / Requires pair will be added on the get / sets for the property. (Ref 2.3.1 of the reference)

You can then use an automatic property in the ContractClassFor 

int Id { get; set; }

(i.e. will still need to add the property, because of the interface)

More here

Upvotes: 2

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