CODEWITHSUNDEEP
c#genericsboxingunboxing
Nelson Rothermel
Nelson Rothermel

Reputation: 9746

Avoid boxing & unboxing in generic class

Below is some quick code to illustrate my question. Any way to avoid this apparently unnecessary boxing/unboxing?

public class TestClass<T>
{
  public T TestMethod()
  {
    if (typeof(T) == typeof(bool))
    {
      return true; // doesn't work
      return (T)(object)true; // works, but any way to avoid this?
    }

    return default(T);
  }
}

Upvotes: 6

Views: 1626

Answers (2)

Tar
Tar

Reputation: 426

Make it a static field.

public class TestClass<T>
{
  static T TrueIfBoolean = typeof(T) == typeof(bool) ? (T)(object)true : default(T)

  public T TestMethod()
  {
    return TrueIfBoolean;
  }
}

That way, the boxing/unboxing only happens once. It's also entirely possible that this kind of optimisation is done by the runtime anyway even in your initial code.

Upvotes: -1

Oded
Oded

Reputation: 499002

This is the only way to handle what you are doing here (returning a non default value for a specific closed generic type).

Upvotes: 4

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