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c#overridingimplicitexplicit

Explicit and implicit for operator (int)

public static explicit operator int(Author a)
    {
        return a.Publications.Length;
    }
    public static implicit operator int(Author a)
    {
        return a.Publications.Length;
    }

why can`t I do this? my teacher asked me to override the implicit and explicit cast for operator int for the Author class. + can I get a explanation for the deep copy :D?

Solution

  • why can`t I do this?

    You can't do that because the C# specification says that you cannot, in section 10.10.3.

    [...] a class or struct cannot declare both an implicit and an explicit conversion operator with the same source and target types.

    Now you might well say:

    Answering a "why" question with "because that's what it says in the spec" is deeply unsatisfying.

    You asked a vague question. If you want a more specific answer then ask a more specific question. How about:

    What factors might the C# design team have considered when creating this rule?

    Any implicit conversion is already a legal explicit conversion. That is, if there is an implicit conversion that allows:

    Shape s = whatever;
Fruit f = s;

    then 

    Fruit f = (Fruit)s;

    is also legal and must mean the same thing. It would be bizarre if those two statements had different semantics, but in a world where you could declare two different versions of the same conversion, one explicit and one implicit, then the compiler would have to detect this situation and ensure that the right conversion is used.

    Conversion logic, particularly user-defined conversion logic, is extremely complex in C#. Removing unnecessary, confusing complications is a good idea.

    can I get a explanation for the deep copy

    Don't ask two questions in one question. Post a second question if you have a second question.