*this
Don
nospam at nospam.com
Fri Apr 24 13:21:22 PDT 2009
Paul D. Anderson wrote:
> Looking at Don Clugston's BigInt code I see usage of "*this":
>
> BigInt opMulAssign(T: BigInt)(T y) {
> *this = mulInternal(*this, y);
> return *this;
> }
>
> I think I know what it does (passes this by reference) but I can't find any documentation that explains the usage. Can anyone point me to a source??
>
> Paul
>
>
It's passing by value, since BigInt is a struct, not a class. 'this' is
a pointer to the struct, so *this is the struct itself. In the case of
BigInt, the struct only contains an bool and a dynamic array, for a
total of 10 bytes or so, so it's not much bigger than a pointer.
I believe the behaviour of 'this' in structs changed recently (but
probably only in D2?) The BigInt wrapper class would be a bit different
in D2.
BTW BigInt uses structs, not classes, and part of the reason for this is
that you _cannot_ have value semantics with a class.
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