🚀 go-pugleaf

Roger Warren wrote:

> if i have TForm1 *Form1 in the host executable, can i pass a pointer
> to an instance of TForm1 to the dll?

If the method is virtual I *think* the DLL will be happy since it
should get the address of the function from the VMT of the object you
are passing in. If OTOH the method is static then the DLL has to have
its own copy of the function since nothing in the VMT tells you where
to find static methods.

An in-memory image of an instantiated object has two main data areas.
The data members you have created are in one and something called a VMT
(Virtual Method Table) is in the other. A VMT is a list of addresses
for all the virtual methods and is how polymorphism works. When you
call a virtual function the compiler generates code to grab its address
from the table and call it.

Static functions are not, by definition, referenced by the VMT so their
address is hard coded by the linker. I'll add that all methods called
while processing a class method will have to be static for the same
reason.

-- 
Andrue Cope [TeamB]
[Bicester, Uk]
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