Thanks but this is a level above what I'm looking for.
I'm trying to communicate between two forms in the same program but do it in
a generic way so that I can re-use one form in many
projects without having to use conditional directives to explicitly state
the name of the other forms.
Less theoretically - I have a form that allows a user to write comments
about some entered data.
I want to use that same form in a data entry program (they can enter
comments as they enter data) and in a reporting/summary view
program (they can add the comments later) and maybe other views later. In
each program I want to show on the entry form or the summary form an
indicator to show that comments exist for this data item. The existence
depends on whether the user adds or deletes
comments in the comments form.
I can set a boolean property on the comments form HasComments := True or
HasComments := False.
How do I get the entry or summary form to immediately recognise that the
property on the comments form has changed? Can I create an event on the
comments form - like OnCommentsChange - and have the entry and summary forms
respond to that event? If so, how do I do that?
----- Original Message -----
From: "James Low" <[EMAIL PROTECTED]>
To: "Multiple recipients of list delphi" <[EMAIL PROTECTED]>
Sent: Tuesday, April 24, 2001 12:21 PM
Subject: RE: [DUG]: Basic OO/Delphi Question
> Have a look at this ... communicating with messages. There may be more
> elgant solutions, but if you "own" both applications (ie other programs
> don't need to query interfaces etc) this is probably the best way to deal
> with interprogram (same machine) coms.
>
> Check out the TMessage type and be careful with your use of the Windows
> constants ... but otherwise messaging between two programs can be pretty
> straightforward.
>
> RECEIVING PROGRAM
>
> unit Unit1;
> interface
> uses
> SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
> Forms, Dialogs, StdCtrls;
> type
> TForm1 = class(TForm)
> Label1: TLabel;
> private
> procedure WMDEBUG(var Msg:TMessage); message WM_USER+2000;
> public
> end;
> var
> Form1: TForm1;
> implementation
> {$R *.DFM}
> procedure TForm1.WMDEBUG(var Msg:TMessage);
> begin
> label1.Caption := 'Received '+PString(Msg.lParam)^;
> end;
> end.
>
>
> SENDING program:
>
> uses WinCrt,WinTypes,Messages,WinProcs;
> var
> S : String;
> begin
> repeat
> Readln(S);
> SendMessage(HWND_BROADCAST,WM_USER+2000,0,Longint(@S));
> until S='';
> end.
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: 24 April 2001 11:46
> To: Multiple recipients of list delphi
> Subject: Re:[DUG]: Basic OO/Delphi Question
>
>
> I may have the wrong end of the stick, as I am not totally sure what you
are
> after, but...
>
> If FormX does not have the lable or caption, you cannot write code (in
> FormX) to
> modify the lable or caption that it does not know about.
>
> Regarding the setting / Getting of a Property - you can write access
methods
> for
> Properties, which if desired, you can override in descendant Forms. That
> should
> produce the desired effect.
>
>
>
> Regards
> Paul McKenzie
>
> =========================
> Paul McKenzie
> Jetbet II Developer
> =========================
> [EMAIL PROTECTED]
> Ph: (04) 576-6822
>
> T.A.B. National Office
> 106-110 Jackson Street
> Petone
> New Zealand
>
>
>
> ____________________Reply Separator____________________
> Subject: [DUG]: Basic OO/Delphi Question
> Author: [EMAIL PROTECTED]
> Date: 24/04/2001 11:32
>
>
>
> I have a form FormX that I want to use in a number of projects.
>
> In, say, Project A I have a form FormA with a label and caption.
> When a change is made to some list or variable on FormX I want to
> modify
> the
> FormA.label.caption
>
> I don't want to do this by writing FormA.label.caption := 'Foo'; in
my
> FormX
> unit
>
> because that won't work when I want to do a similar thing from FormX
to
> FormB in ProjectB.
>
> I know that being able to do this is the benefit of OO but I'm stuck
in
> my
> procedural mindset.
>
> I can make the value I change a property of FormX - but how does
FormA
> or
> FormB know the property has changed?
>
> I'm sure it's simple - just can't see it.
>
> Ideas please.
>
> TIA
> Mike
>
>
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