Reference syntax? (noob)

[Michael Holm]

Calling the function

"float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, type, &point);"
The function is now defined as

float BSpline::Pick(V ector2Coord, float radius, ePickType &type, Vector3
&point){}

I want to be able to change the point class it returns.

What is the syntax for making the "point" a reference that I can change?

Thanks.

//michael

[Jim Langston]

"Michael Holm" <Mi*********@th ismaildontwork. comwrote in message
news:45******** *************** @dread15.news.t ele.dk...

Calling the function

"float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, type, &point);"
The function is now defined as

float BSpline::Pick(V ector2Coord, float radius, ePickType &type, Vector3
&point){}

I want to be able to change the point class it returns.

What is the syntax for making the "point" a reference that I can change?

Thanks.

//michael

Umm..., point is a reference. That's what the & in front of it means.
point is a reference to a Vector3 object.

[LR]

Jim Langston wrote:

"Michael Holm" <Mi*********@th ismaildontwork. comwrote in message
news:45******** *************** @dread15.news.t ele.dk...

>>Calling the function

"float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, type, &point);"
The function is now defined as

float BSpline::Pick(V ector2Coord, float radius, ePickType &type, Vector3
&point){}

I want to be able to change the point class it returns.

What is the syntax for making the "point" a reference that I can change?

Thanks.

//michael

Umm..., point is a reference. That's what the & in front of it means.
point is a reference to a Vector3 object.

That's what I thought at first, but then I figured that might have
missed the.... no, wait, too obvious.

Ok.

In this thing (which won't compile)
float BSpline::Pick(V ector2Coord, float radius, ePickType &type, Vector3
&point){}

Pick is a member function of BSlpine which returns a float. 'point' is
a function parameter (I don't know if that's what it's called formally),
and is in fact, as JL pointed out, a reference. You could change the
object that is being referenced in the function, if that's what you want
to do.

>>Calling the function
float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, type, &point);

Seems to me that it would be unlikely to work.

Suppose we have:

BSpline Splines;
ePickType someType;
Vector3 somePoint;

and then we do this

float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, someType, &somePoint);

is not going to work, because in this context '&somePoint' is trying to
pass the address (ie a pointer) of somePoint to Pick.

Instead, try

float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, someType, somePoint);

Also, Pick will have to return a value. Those empty {} braces shouldn't
compile. I think.

BTW, do you change Splines? If not, then maybe Pick should be const, ie
float BSplines::Pick( Vector2Coord, float radius, ePickType &type,
Vector3 &point) const { return float(0); }

Does type or point change? If not then maybe they should be const too.

float BSplines::Pick(
Vector2Coord, // do you use this in Pick?
float radius, // maybe should be const too?
const ePickType &type,
const Vector3 &point
) const {
return float(0.); //
}

But, if Pick is really returning something called dist, and a point as
well, then you ought to consider doing something like:

std::pair<float ,Vector3BSpline s::Pick(
Vector2Coord,
float radius,
const ePickType &type
) const {
// whatever you need to do, and return
return std::make_pair( 0.f, Vector3());
}

Warning, I haven't tried to compile any of this.

LR

[Salt_Peter]

Michael Holm wrote:

Calling the function

"float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, type, &point);"

remove the address_of operator in front of the point variable in the
call.

>

The function is now defined as

actually, thats a proptotype, not a definition

>
float BSpline::Pick(V ector2Coord, float radius, ePickType &type, Vector3
&point){}

I want to be able to change the point class it returns.

Pick(...) returns a float, did you mean change the Point class it takes
as a parameter?
Did you mean that you want to reseat the reference?

>
What is the syntax for making the "point" a reference that I can change?

references are mutable by nature, what you can't do is reseat it.
Is that Point or point?

>
Thanks.

//michael

[Howard]

"Michael Holm" <Mi*********@th ismaildontwork. comwrote in message
news:45******** *************** @dread15.news.t ele.dk...

Calling the function

"float dist = Splines.Pick(Ve ctor2(x,y), 5.0f, type, &point);"
The function is now defined as

float BSpline::Pick(V ector2Coord, float radius, ePickType &type, Vector3
&point){}

I want to be able to change the point class it returns.

What is the syntax for making the "point" a reference that I can change?

Assuming that you're talking about the third parameter, point, that already
IS a reference. To use it, pass a Vector3 instance, not the address of one.
(In other words, assuming point is a Vector3 object, pass "point", not
"&point".)

What's "Vector2Coo rd"? Is that a typo? Did you mean "Vector2 coord"? If
not, then the type you're passing (a "Vector2") doesn't exactly match a
"Vector2Coo rd" (although there may be some automatic conversion I don't see
here), and also that means you haven't named the first parameter, which
makes it impossible to use inside the function.

Instead of typing code into your posts, try using copy&paste, so that we see
the real code. And let us know exactly what problem you're having. The
function above already uses a reference for the point parameter, so your
question doesn't really make much sense. If you'r problem is that you're
getting a compile error trying to write code to call the function (due to
passing &point instead of point), then you should post the error you're
getting, ok? That way we know what question we're really trying to answer.

-Howard