C# generics syntax for multiple type parameter constraints

Question

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Generic methods and multiple constraints

I need a generic function that has two type constraints, each inheriting from a different base class. I know how to do this with one type:

void foo<T>() where T : BaseClass

However, I don't know how to do this with two types:

void foo<TOne, TTwo>() where TOne : BaseOne // and TTwo : BaseTwo ???

How do you do this? (using .NET 2)

score 860 · Accepted Answer · edited Sep 22 '22 at 15:07

860

void foo<TOne, TTwo>() 
   where TOne : BaseOne
   where TTwo : BaseTwo

edited Sep 22 '22 at 15:07

Mickle-The-Pickle

answered Jun 08 '09 at 15:48

Joel Martinez

11

Search for "Constraining Multiple Parameters" if you don't want to read it all. – RichardOD Jun 08 '09 at 15:51
3

Is it possible to have a constrain that would do this: `void foo() where TOne : Class where TTwo : Class where TOne != TTwo` so basically we don't know what TOne and TTwo are except that they are reference types but cannot be the same – IronHide Jun 23 '16 at 09:20
1

@IronHide: I'd love to be proven wrong here ... but I'm 99% sure this isn't possible :) – Joel Martinez Jul 21 '16 at 19:55
And how to use ExtensionMethod with multiple generics – mincasoft Nov 22 '19 at 15:50

1 Answers1