On 12/20/2010 04:00 PM, David Currie wrote:
I am new to D (like many have done C++ , Java ).
Me too. Let's see what we can figure out together :-)
Can a class be instantiated on the stack ?
eg
class C
{
private int _I1;
private int _I2;
public:
this(int pI) // constructor
{
_I1 = pI;
_I2 = pI + 1;
}
// ... other methods etc
}
void f() // just a function
{
C myC(3); // C++ syntax BUT is there a d equivalent
}
It appears that D ASSUMES myC is really a myC*(in C++)
It is not so much a *, but reference semantics (like T& param in C++).
and therefore requires
C myC = new C(3);
// but this ALWAYS requires calling the memory allocator
// this is what Java does (forces your Class instance onto the Heap)
Is there any way in D to instantiate a stack object ?
Not a class object. Only values are on the stack. The reference
semantics requires a "living" entity to refer to.
Will a struct do?
Yes, if you so wish, but new also works. Structs have value semantics.
Does a struct have a constructor (as opposed to an opcall?)
You can define one, but you cannot redefine the default this()
constructor. Because structs have value semantics, D wants to make sure
that T.init member values are slotted in by default. Note that T.init
for a class type is the null reference.
I would be very grateful for a response.
Hope this helps a bit.
Cheers,
Joost.
David Currie
