Re: computer-go: Delphi Components

[Daniel Hallmark <dgh@xxxxxxxxx>]

On Tue, 4 Jan 2000, Nick Wedd wrote:

> Please excuse my ignorance of Delphi:
> 
> are these components usable only with Delphi code?  Or can they be
> called from, say Visual C++?


I'm not the original poster, but I'll jump in here for a second...

Delphi components are derived from Borland's VCL classes and will work
with Delphi (Object Pascal) or C++Builder (assuming compatible versions 
of the two environments).  The Borland C++ tools will compile MS MFC
code, but I don't know if MS provides similar VCL cross-compatibility 
within their tools.  MS tends to be rather snobbish when it comes to
their proprietary technology... and, apparently, due to the way some of 
the MFC classes are coded, the MS C++ compiler must remain non-compliant 
with certain aspects of the language standard -- specifically with regards
to the scope of local variables declared inside a block of loop code
-- to make the compiler compliant would break existing MFC classes.
So even if it were possible, portability to the MS platform would
require special attention to this and possibly other limitations.

Regardless, there are ways that the components could be used by MSVC.
Windows/Forms can be built using the components and encapsulated in a
DLL which could be used by MSVC.  Or, it is possible to generate an
ActiveX control from a VCL control or form.  This would allow direct use
of the component, but I believe that VCL ActiveX controls are a bit larger 
than non-VCL-based controls because they have to include implementation 
of the appropriate VCL base classes as well as all the ActiveX stuff.

Daniel Hallmark