Re: Total Newbie Backward Compat Question

On Mar 11, 1:21=A0am, Richard Heathfield <r...@[EMAIL PROTECTED]
> wrote:
> Chris ( Val ) said:
>
> <snip>
>
> > Why did you write setters that return values?
>
> int oldx =3D p.setx(newx);
> dosomethingwith(p);
> p.setx(oldx);
>
> is quite a useful thing to be able to do. You can get the same deal
with:

I think I can understand your reasons for it, but that is a hack in
C++, and goes against everything we learn about OOP and writing good,
maintainable and safe code.

Some setters are written to return a 'boolean' value to signal either
success or failure, but even that is debatable in some cir***stances,
when compared to throwing an exception.

It's just too easy to forget how many times it was set, and if it was
a newx or oldx value, and where in the code a mistake was made.

> int oldx =3D p.getx();
> p.setx(newx);
> dosomethingwith(p);
> p.setx(oldx);

This is *much* better, as the 'getter' will always return the current
value, without chance of returning anything other than that.

But why put 'p' through all that trouble?

What you have written above seems to require only a tem****ary, and
could be written as follows, given an appropriate constructor is
implemented:

 dosomethingwith( point( newx ) );

 // p is untouched...

At worst, create a new point as a tem****ary object:

point p2( n, n );

> but only at the expense of an additional function call.

And the advantage of safer programming, easier debugging,
maintenance and conformity to accepted principles and practices.

> --
> Richard Heathfield <http://www.cpax.org.uk>
> Email: -http://www.
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