[boost] Re: class proposal

From: Vincent Finn (vincent.finn_at_[hidden])
Date: 2003-04-23 04:09:20

Justin M. Lewis wrote:
> I don't really know how this works.  I know someone who's a big Boost 
> fan, and he said he didn't know of anything like what I'm going to 
> propose exists in Boost here.  So, here it is.
>  
> The problem I was having, we have references, that allows me to pass a 
> paramter to a function, that function modifies the value passed in, at 
> the point where that function is called, I cannot tell that the data is 
> being modified.  Basically, it leads to somewhat confusing code, 
> especially in a case where you're looking at someone else's code trying 
> to track down where a value gets set.
>  
> void func(int &x){x = 1977;};
>  
> void blah()
> {
>   int y=0;
>   func(y);
>   func2(y);
>   printf("%d\n", y);
> }
>  
>  
> Something along those lines could become confusing, obviously in a much 
> larger program.
>  
> My idea was, if you make a simple template class, originally I called it 
> CRetVal, you could force people to specify at the time the function is 
> called what's going on.  I made a helper template function retval that 
> would create and return a CRetVal object of the desired type to save 
> from needing to use template notation in line all over the place.  So, 
> the above would become something more like.
>  
> void func(CRetVal<int> x){x = 1977;};
>  
> void blah()
> {
>   int y=0;
>   func(retval(y));
>   func2(y);
>   printf("%d\n", y);
> }

could you not get the same effect by using
void func(int* px) {*px = 1977;}

int y = 0;
func(&y);
func2(y);

        Vin