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SD · Guest

Hi to all,

I'm new to patterns matter so I would like if you can
help me to a little question.

I stay to create a CAD/CAM program in which I would
like to use interface paradigm (I use MVP).

My objects (geometric objects, tools, lists) must have
possibility of copy, eg I can copy a complete object
contents in another object.

I know the TPersistent way (Assign) of VCL but I would
like to know if exist a corrispondent or similar concept
in patterns and Interface way.

Thank you...

--
Silverio, SiD Vicenza - Italy
Yahoo Messanger: SiDorDiS

Joanna Carter [TeamB] · Guest

"SD" <nospawm (AT) please (DOT) it> a écrit dans le message de news:
451247ef (AT) newsgroups (DOT) borland.com...

| I'm new to patterns matter so I would like if you can
| help me to a little question.
|
| I stay to create a CAD/CAM program in which I would
| like to use interface paradigm (I use MVP).
|
| My objects (geometric objects, tools, lists) must have
| possibility of copy, eg I can copy a complete object
| contents in another object.
|
| I know the TPersistent way (Assign) of VCL but I would
| like to know if exist a corrispondent or similar concept
| in patterns and Interface way.

Either use Assign which takes an object to copy and assigns the values to
the object with the Assign method; or use Clone which returns the newly
populated object from an exitisn object.

function Clone: TMyType
{
Result := TMyType.Create;
Result.field1 := field1;
...
}

....or you can also create a copy constructor :

type
TMyType = class
private
// fields
public
constructor Create(other: TMyType);
function Clone: TMyType;
...
end;

constructor TMyType.Create(other: TMyType);
begin
inherited Create;
field1 := other.field1
...
end;

function TMyType.Clone: TMyType
{
Result := TMyType.Create(self);
}

Take a look at the Prototype design pattern

Joanna

--
Joanna Carter [TeamB]
Consultant Software Engineer

SD · Guest

Thanks for suggestions !

Jeroen Vandezande · Guest

Hi,

you could also use RTTI to make a more generic Object copy system:

http://www.blong.com/Conferences/BorConUK98/DelphiRTTI/CB140.htm#CopyingPropertiesFromAComponentToAnother

the same can be done in Delphi.net with Reflection...

Best regards,

Jeroen Vandezande

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