What does new() mean in this case? [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicate:

C#: What does new() mean?

I look at definition of E开发者_如何学Pythonnum.TryParse:

public static bool TryParse<TEnum>(string value, out TEnum result) where TEnum : struct, new();

and wondering what new() means here.

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Its a generic type parameter constraint that means that the type for TEnum has to have a public, parameterless constructor.

See here:

http://msdn.microsoft.com/en-us/library/d5x73970.aspx

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it's a constraint to the generic parameter. It means that TEnum must have a parameterless public constructor (and allows you to do new TEnum()). Checkout MSDN page for more details and other type of constraints.

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It is a generic type constraint that requires that the generic type parameter TEnum must support a default constructor (can be newed up without arguments).

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It means that the type TEnum must be able to use

var x = new TEnum();

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It basically says that you can only use this on types which have a public parameterless constructor, ie: where you can do:

var something = new TEnum();

This allows you to enforce that you can create the type internally.

For details, see the C# new Constraint.

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new() as a generic type restriction means that the type used as the generic parameter must have a constructor with the given parameters; here, it must have a parameterless default constructor.