Check Generic Parameters
In a generic type or method definition, a type parameter is a placeholder for a specific type that a client specifies when they create an instance of the generic type. A generic class, such as GenericList<T>
listed in Introduction to Generics, cannot be used as-is because it is not really a type; it is more like a blueprint for a type. To use GenericList<T>
, client code must declare and instantiate a constructed type by specifying a type argument inside the angle brackets. The type argument for this particular class can be any type recognized by the compiler. Any number of constructed type instances can be created, each one using a different type argument, as follows:
For instance:
GenericList<float> list1 = new GenericList<float>();
GenericList<ExampleClass> list2 = new GenericList<ExampleClass>();
GenericList<ExampleStruct> list3 = new GenericList<ExampleStruct>();
In each of these instances of GenericList, every occurrence of T in the class is substituted at run time with the type argument. By means of this substitution, we have created three separate type-safe and efficient objects using a single class definition. For more information on how this substitution is performed by the CLR
In addition to the above, you can also have constraints about the type that T
can be.
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