We can add constraints to generic type parameters with the following syntax.
where: constraint
The constraints can be the follows:
| Constraint | Meaning |
|---|---|
| where T : base-class | Base class constraint |
| where T : interface | Interface constraint |
| where T : class | Reference-type constraint |
| where T : struct | Value-type constraint |
| where T : new() | Parameterless constructor constraint |
| where U : T | Naked type constraint |
using System;
class Shape{
}
class Rectangle: Shape{
}
class Circle: Shape{
}
class GenericClass<T> where T : Shape{
}
class Test
{
static void Main()
{
GenericClass<Rectangle> g = new GenericClass<Rectangle>();
}
}
interface constraint
using System;
interface PrintTable{
void print();
}
class Rectangle : PrintTable
{
}
class GenericClass<T> where T : PrintTable
{
}
class Test
{
static void Main()
{
GenericClass<Rectangle> g = new GenericClass<Rectangle>();
}
}
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