EnumerableOfType

EnumerableOfType refers to the LINQ extension method OfType<T>, defined in System.Linq. Enumerable.OfType<TResult>(this IEnumerable source) returns all elements of the input sequence that are of type TResult, discarding any that are not. It operates on non-generic sequences as well as generic ones and yields the results with deferred execution.

The method filters by runtime type. As it enumerates the source, it checks each element: if the element is of type TResult (or a type assignable to TResult), it is emitted; otherwise it is skipped. Null values are not yielded, since null is not considered an instance of a reference type in a type test.

OfType<T> supports any reference type as TResult and any value type as well where appropriate. If the source contains elements of multiple types, OfType returns only those elements whose type matches TResult, preserving the original order. It is often used to extract a homogeneous subset from heterogeneous collections such as ArrayList or objects retrieved from dynamic sources.

Compared with Cast<T>, OfType<T> does not throw on elements that cannot be cast. Cast attempts to cast every element and raises an exception for incompatible items, while OfType simply filters them out.

For IQueryable sequences, a similar operator exists as Queryable.OfType<TResult>, enabling type-based filtering in provider-based queries. Example: var strings = someCollection.OfType<string>(); yields only string elements from the collection.

In summary, EnumerableOfType provides a safe, deferred-execution means to select elements of a specific type from a sequence, useful for working with mixed-type data.