Copying structs via function (not bitwise)

[Bill Baxter]

Matthias Walter wrote:
> Is there any other way of copying structs with '=' operator, other than the default way of a bitwise copy? I quote the FAQ:
> 
> "Structs, being value objects, do get copied about. A copy is defined in D to be a bit copy. I've never been comfortable with any object in C++ that does something other than a bit copy when copied. Most of this other behavior stems from that old problem of trying to manage memory. Absent that, there doesn't seem to be a compelling rationale for having anything other than a bit copy."
> 
> The reason, I'm asking for this, is that I'm working on a GMP port. Because numbers _must_ be value types, I must use structs. But as different instances of the same number must reference another memory region of the GMP internals, I must call special copy functions, if I do "a = b;" on two gmp-structs, a refers to the same gmp-internal memory as b.
> 
> Is there any way to do this?
> 
> best regards
> Matthias Walter

opAssign can be used to override the meaning of A=B where A and B are 
different types.  But by design you can't change the meaning A=B where A 
and B are the same type.

But you could make it work using any of the following:

A ~= B;
A.foo = B;
A = B.foo;
assign(A,B);
A.assign(B);
etc..

And I'm sure downs could suggest a few more workable syntaxes. :-)

--bb