Re: Beginner's Question: Global class variable without default constructor

From:
Werner Schmidt <inno1NOSP@M.gmx.de>
Newsgroups:
microsoft.public.vc.language
Date:
Tue, 10 Mar 2009 15:41:30 +0100
Message-ID:
<uCCt$4YoJHA.4028@TK2MSFTNGP03.phx.gbl>
I wrote:

(and to be honest: I'm not sure if throwing an exception would be
good practice under C#).


After some thinking I've come to the conclusion that this would be
good-practice. If a user tries to pass an empty value (NULL) to my
constructor this is (in this case) a not to tolerate behaviour and worth
to throw an exception.

Of course I can check my value *before* calling my constructor

[CODE]
// main.cpp
if (hWnd != NULL) {
    game = new Game(hWnd);
}
[/CODE]

but this would mean to trust in something from *outside* my object which
I want to be handled *through* my object.

I would implement something like

[CODE]
Game::Game(HWND hWndMain)
{
    if (hWndMain == NULL) {
        throw new UnexpectedNullValueException;
    }

    //
    // etc.
    //

}
[/CODE]

(I don't know if there is an equal exception in C++ already but just for
example).

Of cource someone could do sth. like

[CODE]
// main.cpp
try {
    game = new Game(NULL);
} catch () {}
[/CODE]

to fool my constructor but throwing an exception is all I can do.

Just my two cents

Werner

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