Re: [UOPL-Architect] how design uopl gui applications

[Richard B W. <rb...@us...>]

When I tried to use this technique, the component compiled OK but I got an
access violation when I tried to install the component.  This is what I
expected. I believe that this means if UOPL starts from anything below
TComponent, it will not be possible to place the UOPL components on the
component palette.

Here is what I did.

1. I copied a Classes into a new unit called MyClasses
2. In MyClasses, I changed the ancestor of TComponent from TPersistent to
TInterfacedPersistent.
3. I changed the declaration of QueryInterface to override the declaration
in TInterfacedPersistent.

before
    function QueryInterface(const IID: TGUID; out Obj): HResult; virtual;
stdcall;
after
    function QueryInterface(const IID: TGUID; out Obj): HResult; override;
stdcall;

4. I created a component in a new unit that used the version of TComponent
in MyClasses.

Here is a copy of that unit.

unit ExperimentUnit;

interface

uses Classes, MyClasses;

type
  TExperimentComponent = class(TComponent)
  private
    FInt1: integer;
    procedure SetInt1(const Value: integer);
  published
    property Int1: integer read FInt1 write SetInt1;
  end;

procedure Register;

implementation

procedure Register;
begin
  Classes.RegisterComponents('Experiments',
    [Classes.TComponentClass(TExperimentComponent)]);
end;

{ TExperimentComponent }

procedure TExperimentComponent.SetInt1(const Value: integer);
begin
  FInt1 := Value;
end;

end.

Richard B. Winston
rb...@us...
http://water.usgs.gov/nrp/gwsoftware/
703-648-5988
on Fridays: 301 474-2762


                                                                                                                                      
                      "Dennis Landi"                                                                                                  
                      <de...@de...>               To:       <uop...@li...>                         
                      Sent by:                               cc:                                                                      
                      uop...@li...        Subject:  Re: [UOPL-Architect] how design uopl gui applications          
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                      12/03/2004 01:48 PM                                                                                             
                      Please respond to                                                                                               
                      uopl-architect                                                                                                  
                                                                                                                                      
                                                                                                                                      




Re: the tInterfacedPersistent -->> tInterfacedComponent descendants being
registerable.

It will be interesting to see if a tInterfacedComponent replica of the
TComponent interface is registerable.

I don't see why it wouldn't be...  It will be an easy enough experiment to
run.

You would simply have to typecast it in the Registration proc.

The registration syntax would be:

  RegisterComponents('MyComponentPage',[tComponentClass(TMyComponent)]);

The interfaces of both artifacts would have to match; and if so, the IDE
registration mechanism probably won't notice.

This means that would have to hack the original source of tComponent; and
clone a tInterfaceComponent version; which we would probably have to only
be
able to distribute as a DCU...  But, I don't see that as a show-stopper.

If the technique works, then we can actually introduce it to the delphi
community, as it will allow them to unify artificacts at the component
level, which will come in really handy for things like plug-ins.



Dennis Landi
Allied Data, Inc.
800 204 2722
http://www.dennislandi.com




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