Creating Custom LINQ Operators

LINQ (Language Integrated Query) provides a wide range of built-in operators to work with collections. However, sometimes we need to create our own custom operators to perform operations specific to our application. In this article, we will learn how to create custom LINQ operators.

Syntax

public static <return type> CustomOperator<TSource>(this IEnumerable<TSource> source, <parameters>)
{
    // Custom operator logic
    return <return value>;
}

Example

Let's create a custom LINQ operator that will return all even numbers from the integer collection.

public static IEnumerable<int> GetAllEvenNumbers(this IEnumerable<int> source)
{
    foreach (int i in source)
    {
        if (i % 2 == 0)
        {
            yield return i;
        }
    }
}

Explanation

In the above example, we have created a static extension method named GetAllEvenNumbers() that takes an integer collection as input and returns all even numbers from the collection.

We've used a foreach loop to iterate over the collection and filter out even numbers using the modulo operator. And instead of returning a list, we've used the yield return keyword to lazily return the values as an IEnumerable<int>.

Use

Custom LINQ operators are useful when we need to perform operations specific to our application that are not covered by the built-in LINQ operators. We can leverage the power of LINQ by creating our own custom operators.

Important Points

• Custom LINQ operators should be created as static extension methods.
• Custom operators should return an IEnumerable<T> or IQueryable<T> to ensure compatibility with other LINQ operators.
• Custom operators should not modify the original collection.

Summary

In this article, we learned about creating custom LINQ operators. We saw the syntax and example of a custom operator that returns all even numbers from a collection of integers. Custom LINQ operators can help us perform operations specific to our application that are not covered by the built-in LINQ operators. However, we should be careful while creating custom operators and ensure compatibility with other LINQ operators to maintain the power and flexibility of LINQ.