title: BL0005 - external parameter usage - why is a warning for that?
body: <blockquote>
    <p>BL0005:Component parameter should not be set outside of its component.</p>
  </blockquote>
  
  <p>I have a component inside a component. When my outer component state changes, I want to update inner component's state. The outside component is an autocomplete implementation, the state that changes is input text, the inner component is autocomplete items list, its highlighted part to be exact.</p>
  
  <p>So I change the inner component state via its parameter. And I get this warning. Why?</p>
  
  <p>BTW, the code works exactly as I expected it to work. The state is synchronized, my matched text is highlighted in all autocomplete items.</p>
  
  <p>My guess is changing the parameter could cause the component to re-render itself, which is, in my case - completely desired and expected behavior. Why else would I change a parameter of a component at runtime?</p>
  
  <p>I searched for the warning online, but I haven't found anything useful beside that one:
  <a href="https://github.com/aspnet/AspNetCore/issues/12293" rel="noreferrer">https://github.com/aspnet/AspNetCore/issues/12293</a></p>
  
  <p>Again, it looks like modifying the parameter the way I do in my code is a very bad practice, but again, WHY? Is there a reason I have to do that in less simple and straightforward way, or there is MORE simple and straightforward way of doing this?</p>