lvalue forwarding struct?

[Bill Baxter]

Chad J wrote:
> What I am looking for is a templated struct that simply wraps a 
> variable, and ensures lvalueness is preserved for that variable.
> Ex:
> 
> foo(bar) *= 9;
> 
> In this case foo is to be a function that acts on bar, and then makes 
> sure that bar has the *= 9; applied to it.
> 
> It might look like this:
> 
> int foo(inout int input)
> {
>   input++;
>   return lvalue(input);
> /* lvalue(...) is an opCall constructor for the lvalue templated 
> forwarding struct.  */
> }

It certainly isn't going to work if you return 'int'.

> Thus we could write
> 
> int bar = 3;
> foo(bar) *= 9;
> printf( "%d", bar ); // prints 36
> 
> One possible use case would be as a hack to get around certain 
> shortcomings of properties for the time being.
> 
> So does anyone have such a thing that they want to share?
> Otherwise this is something I might do.

I think you should take a look at the code posted by Reiner the other 
day in digitalmars.D under the subject "Proxy objects and 
controlling/monitoring access".  The thread starts with the message 
Xref: digitalmars.com digitalmars.D:57028

--bb