re-creating C++'s reference bahavior

[akcom]

> AFAIK, there's really no way to exactly duplicate C++'s references.
> However, if all "position()" is doing is returning a reference to a
> vector, then do you really need a function at all?  If you just use a
> member variable, then the problem disappears.

What about situations in which you're not just returning a reference to a 
class object?  A templated hash map implementation for example, may want to 
do something like the D equivalent of
template <class T, class K >T &HashMap<T,K>::find( K )

Things become a bit trickier if you're dealing with basic types.

"Daniel Keep" <daniel.keep.lists at gmail.com> wrote in message 
news:f0160f$bau$1 at digitalmars.com...
>
>
> swiftcoder - Tristam MacDonald wrote:
>> I am fairly new to D, from a C++ background, and I am having a hard time 
>> coming up with a sensible way to deal with what is a fairly trivial 
>> example in C++:
>>
>> class Vector3f;
>>
>> class Node
>> {
>> Vector3f &position();
>> };
>>
>> Node n;
>>
>> n.position().x = 0; // Works as expected, sets n.position().x to 0
>>
>> Vector3f v = n.position();
>> v.x = 10; // Works as expected in C++ since v is a copy of n.position()
>>
>> But now in D, I find that the last statement requires an explicit copy on 
>> the user's part, otherwise they are using the actual instance, and may do 
>> nasty things to it unintentionally. The obvious fix is to copy the vector 
>> in Node.position(), but then you have lost the benefits of references, 
>> namely to modify the variable. So it would seem that the only way to 
>> handle this is to return a copy in the getter function, and  require 
>> explicit setting with the setter method (thus losing constructs such as 
>> n.position().x = 0)?
>
>
> And incidentally, you can omit the parens with D since it's a function
> with no arguments. ie:
>
>> auto v = n.position;
>> v.x = 10;
>
> ("auto" is used here to trigger type inference -- if you specify a
> variable's storage class, you can omit the type itself.)
>
> -- Daniel
>
> -- 
> int getRandomNumber()
> {
>    return 4; // chosen by fair dice roll.
>              // guaranteed to be random.
> }
>
> http://xkcd.com/
>
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