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Alt text:

A screenshot from the linked article titled “Reflection in C++26”, showing reflection as one of the bullet points listed in the “Core Language” section

    • JakenVeina@lemm.eeEnglish
      4·
      2 months ago

      It’s the capability of a program to “reflect” upon itself, I.E. to inspect and understand its own code.

      As an example, In C# you can write a class…

      public class MyClass
{
    public void MyMethod()
    {
        ...
    }
}

      …and you can create an instance of it, and use it, like this…

      var myClass = new MyClass();
myClass.MyMethod();

      Simple enough, nothing we haven’t all seen before.

      But you can do the same thing with reflection, as such…

      var type = System.Reflection.Assembly.GetExecutingAssembly()
    .GetType("MyClass");

var constructor = type.GetConstructor(Array.Empty<Type>());

var instance = constructor.Invoke(Array.Empty<Object>());

var method = type.GetMethod("MyMethod");

var delegate = method.CreateDelegate(typeof(Action), instance);

delegate.DynamicInvoke(Array.Empty<object>());

      Obnoxious and verbose and tossing basically all type safety out the window, but it does enable some pretty crazy interesting things. Like self-discovery and dynamic loading of plugins, or self-configuration of apps. Also often useful when messing with generics. I could dig up some practical use-cases, if you’re curious.

        • Zangoose@lemmy.worldOP
          0·
          2 months ago

          It’s pretty cool when you use it right but it’s also really easy to shoot yourself in the foot with, even by C++ standards. For example, in other languages (I’m coming from Java/C# which both have it) it lets you access private/protected fields and methods when you normally wouldn’t be able to.

          There’s also a noticeable performance penalty over large lists because you’re searching for the field with a string instead of directly accessing it.

          For the times it is necessary (usually serialization-adjacent or dynamic filtering/sorting in a table) to use reflection, it’s faster at runtime than converting an object to a dictionary/hashmap. However, 99% of time it’s a bad call.