Non-virtual private struct inheritance

[monarch_dodra]

On Thursday, 23 August 2012 at 13:17:23 UTC, bearophile wrote:
> monarch_dodra:
>
>> In C++, it is a very common practice, when writing a struct 
>> template, to have said template derive from a base 
>> non-template struct. This makes sure there is no executable 
>> bloat,
>
> "alias this" seems to help both for composition and against 
> template bloat:
>
>
> struct Foo {
>     int x;
>     int bar() { return x * 2; }
> }
> struct Bar(T) {
>     Foo f;
>     T y;
>     alias f this;
> }
> void main() {
>     Bar!int b1;
>     b1.x = 10;
>     assert(b1.bar() == 20);
>     Bar!double b2;
>     b2.x = 100;
>     assert(b2.bar() == 200);
> }
>
>
> In the asm listing there is only one bar:
>
> _D3foo3Foo3barMFZi:
>     enter 4, 0
>     mov EAX, [EAX]
>     add EAX, EAX
>     leave
>     ret
>
>
> Another way to fight template bloat is the @templated() I have 
> suggested elsewhere, that applied to something inside a 
> template allows you to choose what that something is templated 
> to (even nothing).
>
> Bye,
> bearophile

Thanks for the answer. Very nice. "alias this" is still the first 
thing I think about, but in this case, it works perfectly well 
actually.