Re: A question on the RECT struct

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Dom wrote:
I hope I'm not a pest, but I guess the question I have is better put
this way: Since there are already 3 overloads for the Rectangle
constructor, why isn't there just a fourth that takes the LTRB args?
I'm just confused about the two calls, one to a constructor, one to a
method.

Here's the declaration for the constructor that takes the top-left coordinates and the size:

public Rectangle(int x, int y, int width, int height);

Here's the declaration for the constructor that takes the top-left and bottom-right coordinates:

public Rectangle(int xLeft, int yTop, int xRight, int yBottom);

Here's some code that uses these constructors:

// initialize with top-left and size:
Rectangle rectA = new Rectangle(10, 20, 30, 30);

// initialize with top-left and bottom-right:
Rectangle rectB = new Rectangle(10, 20, 40, 50);

Now, imagine you're the compiler. In the above code example, how do you know which constructor goes with which assignment?

That should illustrate the issue, but just in case:

The reason that the constructor exists for one and not the other is that both are method signatures that takes four integers and return a Rectangle. You can't have two constructors with identical signatures, so at least one of the methods cannot be a constructor. It has to be a plain static method that returns a Rectangle.

Now, a valid question might be: why not forego the constructor altogether and make things consistent by making all of the initialization methods be plain static methods.

IMHO, the answer to that is that a constructor really is a preferable way to initialize an object (it's a lot more discoverable, especially via Intellisense, for one), and so it's worth making as many of the initialization methods be constructors.

That's one possible answer. I don't know if that's the actual reason for the current design, but it seems plausible to me.

Pete
.

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