Tuple.Create() vs new Tuple

问题

Consider the following expressions:

new Tuple<int,int>(1,2);

Tuple.Create(1,2);

Is there any difference between these two methods of Tuple creation? From my reading it seems to be more a convenient shorthand than anything like object creation in C++ (heap vs stack).

回答1:

Well, this questions is old... but nevertheless I think I may contribute constructively. From the accepted answer:

I suppose one benefit is that, since you don't have to specify the type with Tuple.Create, you can store anonymous types for which you otherwise wouldn't be able to say what the type is

The consequence is true: you can store anonymous types for which ...

But the first part:

since you don't have to specify the type with Tuple.Create

is not always true. Consider the following scenario:

interface IAnimal
{
}

class Dog : IAnimal
{
}

The following will not compile:

Tuple<IAnimal> myWeirdTuple;

myWeirdTuple = Tuple.Create(new Dog());

You will have to specify the type parameter in the Create method like this:

myWeirdTuple = Tuple.Create<IAnimal>(new Dog());

which is as verbose as calling new Tuple<IAnimal>(new Dog()) IMO

回答2:

Personally, I find Tuple.Create() less verbose and easier to read.

There's no difference, under the hood. The Tuple.Create() overloaded methods are just a bunch of static methods that call the first version you posted:

public static class Tuple
{
    public static Tuple<T1> Create<T1>(T1 item1) {
        return new Tuple<T1>(item1);
    }

    public static Tuple<T1, T2> Create<T1, T2>(T1 item1, T2 item2) {
        return new Tuple<T1, T2>(item1, item2);
    }

    public static Tuple<T1, T2, T3> Create<T1, T2, T3>(T1 item1, T2 item2, T3 item3) {
        return new Tuple<T1, T2, T3>(item1, item2, item3);
    }

    ...

I suppose one benefit is that, since you don't have to specify the type with Tuple.Create, you can store anonymous types for which you otherwise wouldn't be able to say what the type is.

public class Person
{
    public string Name { get; set; }
    public int Height { get; set; }
    public DateTime BirthDate { get; set; }
}

var people = new List<Person>
{
    new Person { Name = "Bob", Height = 72, BirthDate = new DateTime(1984,1,1) },
    new Person { Name = "Mary", Height = 64, BirthDate = new DateTime(1980,2,2) }
};

var oneAnonList = people.Select(x => new { x.Name, x.BirthDate });
var twoAnonList = people.Select(x => new { x.Height, x.Name });

var myTuple = Tuple.Create(oneAnonList, twoAnonList);

This creates a Tuple with two anonymous types, the first is a new { string Name, DateTime BirthDate } and the second is a new { int Height, string Name }.

There's still not too terribly much you can do with that, since to pass it to another method, you'd still need to be able to define the "type" of the parameter. So it really comes down to convenience.

回答3:

The benefit of Tuple.Create is that you can usually omit the type arguments, eg. Tuple.Create(1,2) is briefer than new Tuple<int,int>(1,2).

If you try omitting the type arguments from the constructor new Tuple(1,2) you will see error CS0712 "Cannot create an instance of the static class 'Tuple""

回答4:

There is no difference. If you take a look at the source code, it is doing the same thing.

http://referencesource.microsoft.com/#mscorlib/system/tuple.cs,9124c4bea9ab0199

For example:

Tuple.create(1,2);

is going to call

   public static Tuple<T1, T2> Create<T1, T2>(T1 item1, T2 item2) {
        return new Tuple<T1, T2>(item1, item2);
    }

回答5:

Starting with C# 7, you can now simply declare Value Tuple like so:

var unnamed = (1, 2);

var named = (name: "Joe", age: 2);

See microsoft documentation here: https://docs.microsoft.com/en-us/dotnet/csharp/tuples

来源：https://stackoverflow.com/questions/27455581/tuple-create-vs-new-tuple

标签

tuples