Hi,
I'm translating one application from delphi to lazarus, and I'm having some problems with the way lazarus and delphi stores calculate fields in the dfm.
The delphi store one more property :"Calculated". This property is public and are stored using the procedure DefineProperties at TField level.

dfm example :
Delphi :
object DetailsTOTAL: TFloatField
FieldKind = fkCalculated
FieldName = 'TOTAL'
DisplayFormat = '0.00'
* Calculated = True*

    end

Lazarus :
object DetailsTOTAL: TFloatField
FieldKind = fkCalculated
FieldName = 'TOTAL'
DisplayFormat = '0.00'

    end

Any easy way to solve the problem ?

ps :
The application must compile on both compilers.
Lazarus version 1.1 with FPC 2.6.1. SVN Revision : 39433

Thx
jGoncalves
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lazarus.freepascal.org/pipermail/lazarus/attachments/20121213/3e2a0790/attachment.html>

Bit of a hack, but you could use the Tag property as a boolean on Lazarus. Its published, so is stored in the .lfm. But obviously this would require {$IFDEF } to compile on Delphi too.

What does "Calculated" do?

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lazarus.freepascal.org/pipermail/lazarus/attachments/20121214/ac584928/attachment.html>

Kostas Michalopoulos wrote

What does "Calculated" do?

Judging from the Delphi code, it is no longer used. The GetCalculated returns

function TField.GetCalculated: Boolean;
begin
   Result := FFieldKind = fkCalculated;
end;

And setcalculated does:

procedure TField.SetCalculated(Value: Boolean);
begin
   if Value then
     FieldKind := fkCalculated
   else if FieldKind = fkCalculated then
     FieldKind := fkData;
end;

So it can safely be ignored.

Michael.

Yes i know.
The problem surges when we read the dfm. The reader will give one exception that the property is unknown.
If we try to remove the property from the file, Delphi will introduce them again, next time we edit the datamoudule.

jGoncalves
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lazarus.freepascal.org/pipermail/lazarus/attachments/20121214/45c284f2/attachment.html>

I added an ignore in lcl/dbctrls.pp:
  RegisterPropertyToSkip(TField,'Calculated','VCL compatibility property', '');

Please test.

Mattias

You can install an unknown property event handler in TReader: OnPropertyNotFound

But that requires that you are able to choose which reader is used, because now you cannot: I've long wanted to install a hook so you can select which reader/writer is used in TStream.ReadComponent.

Maybe the lazarus implementation offers a hook ?

Michael.

Maybe you mean in unit lresources.pp:
  LRSObjectReaderClass: TLRSObjectReaderClass=TLRSObjectReader;
  LRSObjectWriterClass: TLRSObjectWriterClass=TLRSObjectWriter;

Mattias

Something like it, and also the hooks you posted in your other reply.

I think that the 2 variables you post above can be moved to the classes unit: ObjectReaderClass and ObjectWriterClass. These should then be used in the TStream.ReadComponent and TStream.WriteComponent.

That's what I meant with the 'install a hook'.

Once it is in place, the LCL can simply set these hooks, and remove any custom hooks you made.

Michael.

Worked ....
for now I'm using on my own unit as a temporary hack.

Thx
jGoncalves

On Fri, Dec 14, 2012 at 10:21 AM, Mattias Gaertner <

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lazarus.freepascal.org/pipermail/lazarus/attachments/20121214/29d3a0dd/attachment.html>