Myles, This is not quite correct?
Mmmm, maybe I am just being pedantic but further on my email did actually mention that you could achieve this by using RTTI. However I don't think it is a good solution as it is comparitively slow, bypasses the normal type checking and is just generally "messy". I also gave an example of how to achieve it by using interfaces.... Cheers, David. > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Behalf Of Myles Penlington > Sent: Wednesday, 26 February 2003 12:18 PM > To: Multiple recipients of list delphi > Subject: RE: [DUG]: How do I refer back to a calling form? > > > > >To answer your question tho... there isn't really any way that > you can get > >the code in DatabaseUtils.pas to directly access properties declared in > >TMainForm without having MainForm.pas in your uses clause (which > obviously > >you don't want for generic database utilities). Having said that > there are > >various options. You could define a generic form class which has the UV > >property and then descend TMainForm from it. eg, > > This is not quite correct. You can do this with RTTI (have to declare > property as published) - I have done it before to stop circular references > between units and packages - it's not nice, but does have it uses. > eg > To set a "PUBLISHED" event property on a class without having a > reference > in the units uses clause. > > if Assigned( Application.MainForm ) and > Application.MainForm.ClassNameIs('TApplicationMainForm') then begin > Method.Code := @TDataUnit.OnEnvironmentChanged; > Method.Data := Self; > SetMethodProp( Application.MainForm, 'OnEnvironmentChange', Method ); > end; > > Of course a cleaner way would be to use interfaces to achieve the > same thing > (why didn't I think of that at the time)??? > > eg > Something like. > > if Assigned( Application.MainForm ) and Application.MainForm.Supports( > IMyEnvironmentInterface) then > IMyEnvironmentInterface := Application.MainForm; > IMyEnvironmentInterface.OnEnvironmentChange := > Self.OnEnvironmentChanged > end; > > > Myles. > > > ------------------------------------------------------------------ > --------- > New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] > Website: http://www.delphi.org.nz > To UnSub, send email to: [EMAIL PROTECTED] > with body of "unsubscribe delphi" > Web Archive at: http://www.mail-archive.com/delphi%40delphi.org.nz/ --------------------------------------------------------------------------- New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz To UnSub, send email to: [EMAIL PROTECTED] with body of "unsubscribe delphi" Web Archive at: http://www.mail-archive.com/delphi%40delphi.org.nz/
