Question about Tut 19

[zokerus]

Hello Guys,
I have a question concerning tutorial no. 19. In this tutorial Chili introduces the Vec2 class and at the point 18:05 min he changes the constructor parameter of the poo class. I don't understand why he users a reference of the Vec2.

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void Init(const Vector2& pos_in, const Vector2& vel_in);

I my mind, by using a reference of this Vec2 parameter would create a invalid reference as soon as the origin is disposed, but this don't happen.

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poos[i].Init(Vector2(xDist( rng ),yDist( rng )),Vector2(vDist( rng ),vDist( rng )));

Can someone explain it to me??

Best regards,
zokerus

[SlevinKelevra]

The big advantage of passing by reference is that a copy of the argument is not made. It is fast, even when used with large structs or classes. Const reference does not allow you to change the value.

In the Init function the two Vec2 (pos and vel) are copied to the poo members. The reference values are not used anymore from then on.

[chili]

I my mind, by using a reference of this Vec2 parameter would create a invalid reference as soon as the origin is disposed, but this don't happen.

Code: Select all

poos[i].Init(Vector2(xDist( rng ),yDist( rng )),Vector2(vDist( rng ),vDist( rng )));

Can someone explain it to me??

Best regards,
zokerus

When you initialize a variable with a reference to another variable, it copies the value of the referenced variable into the variable for initialization. The variable that is to be initialized does not transform into a reference. Also, references behave exactly like normal variables after they are initialized, so you don't have to worry about that.

The only time you would have a problem of invalid reference is if the member that is being initialized is a reference.

[zokerus]

Hi Guys,
thank you for your quick response. Now I understand what you did there and I can continue with the tutorials.

Thank you and best regards,
Zokerus