C#•10mo ago

✅ Why is an explicit cast needed even though the implicit cast operator is available?

No explicit cast is needed.

var (x, y) = GetPoint();
static (float re, float im) GetPoint() => (1, 0);

var (x, y) = GetPoint();
static (float re, float im) GetPoint() => (1, 0);

But why does the following need explicit cast even though an implicit conversion operator has been implemented?

//var (x, y) = new Complex(1, 0); <== Error!

var (x, y) = ((float, float))new Complex(1, 0);

class Complex(float re, float im)
{
    public float Re { get; set; } = re;
    public float Im { get; set; } = im;
    public static implicit operator (float re, float im)(Complex c) => (c.Re, c.Im);
}

//var (x, y) = new Complex(1, 0); <== Error!

var (x, y) = ((float, float))new Complex(1, 0);

class Complex(float re, float im)
{
    public float Re { get; set; } = re;
    public float Im { get; set; } = im;
    public static implicit operator (float re, float im)(Complex c) => (c.Re, c.Im);
}

5 Replies

JochCool•10mo ago

I think it's because the syntax var (x, y) is deconstruction syntax, so it will try to call a destructor

jcotton42•10mo ago

var (x, y) = is performing a deconstr--yeah that it's not creating a tuple

JochCool•10mo ago

This works:

C#
(float, float) variable = new Complex(1, 0);

C#
(float, float) variable = new Complex(1, 0);

jcotton42•10mo ago

https://learn.microsoft.com/en-us/dotnet/csharp/fundamentals/functional/deconstruct

Deconstructing tuples and other types - C#

Learn how to deconstruct tuples and other types.

i like chatgptOP•10mo ago

Ok. Thanks.

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✅ Why is an explicit cast needed even though the implicit cast operator is available?