CODEWITHSUNDEEP
c#.net
Davide Lettieri
Davide Lettieri

Reputation: 326

Constraints on method declared in Interfaces

Is there a way to ask that a method result respect a certain property? such as

interface MyInterface()
{
    int MyMethod(int a, int b);
    // i want that my int result is less then 10
}

I want to enforce in the definition this kind of request. Is it possible?

Upvotes: 1

Views: 61

Answers (2)

aL3891
aL3891

Reputation: 6275

That is not possible using interfaces in c# unfortunately. You could have the caller of the interface enforce this or you use an abstract class instead:

abstract class MybaseClass()
{
    protected virtual int MyMethodInternal(int a, int b){ //this method is not visible to the outside
     // implementors override this
    }

    public sealed int MyMethod(int a, int b){ // users call this method
    var res = MyMethodInternal(a,b);
    if(res < 10)
        throw new Exception("bad implementation!");
    }
}

Upvotes: 2

Baldrick
Baldrick

Reputation: 11840

No, that's not possible. The contract simply doesn't define those kinds of constraints.

Interface constraints are checked at compile time, the return value of a function cannot in general be known by the compiler.

Upvotes: 0

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