[fpc-pascal]Classes and copying

[Matt D. Emson]

> This indeed only copies the pointer. if you want to do more 
> than that, then you need to implement this yourself.
> 
> TPersistent implements the 'Assign' method for this. You can 
> create a descendent from TPersistent, override the Assign 
> method, and then copy fields as necessary in the new Assign method.


And also that, whilst this sounds tedious, you could (in Delphi mode
only I guess) use RTTI to automate some of it. There is at least one
component (have a look for zproplst.zip on Torry.net, or if you have the
Delphi source there is a hidden TPropList class) that goes through the
published members and gets all their names and types. You can then use
the routines in the unit Typinfo (might be part of fcl I guess, should
be in the Delphi compatible part of the RTL at least though) to retrieve
and set their values. Caveat, you *must* declare all members that you
with to get at as being Published, it only really works well for
properties and your classes should descend from Tpersistent.

Having said all that, it works really well in Delphi, and I assume
Delphi mode (S2 or Sd). Does the TP or the ObjFPC mode support RTTI and
the Typinfo unit?

Noting also that whilst C++ has a nice syntax for this (the 'copy'
constructor/operator overloading dodge) all it really does is the same
as Assign (mostly) but just in a more convoluted way.

Matt