Hi,

first of all, as it's the first time I write here, I'd like to thank all the people involved in the development/testing/mantaining/etc of Lazarus :-)

I would like to understand better how to deal with the properties of a visual component. My problem is the following: I'm writing a component that has a property of class TStringList. This property is published, so I can correctly access at design-time when I put my new component in a form. But if I assign some values to the TStringList at design-time, it seems that at run time that string list is empty.

Now, if I initialize that list through code (it means that I do this run time, after the component is created) everything is fine. My doubt is that in the constructor of the component the string list is created and initialized, so maybe this is the problem. But if I don't create the string list in the constructor of the component, of course I have an error.

Can someone please explain me how properties of a component are managed at design-time? How can I set my string list at design-time and correctly have the values available at run-time?

Thanks!

A.

Never use TStringList as a property type, always use TStrings. (but initialize your field with a TStringList instance)

The write must always happen through a setter procedure, and in the setter you must assign the strings:

   Property MyProp : TStrings Read FMyProp Write SetMyProp;

Where SetMyProp is implemented as

Procedure TmYCOmponent.SetMyProp(AValue : TStrings);
begin
   if FMyProp=AValue then exit;
   FMyProp.Assign(AValue);
end;

Michael.

Dear Michael,

thanks for your reply. But actually I already did what you suggested! Luckily your message made me think again and I found out that the problem was not there: information int the string list was correclty stored even when inserting these strings
were needed to add some voices in a popup menu, and this was the point where things went wrong (and as I didn't see the changes in the popup, I was thinking that the string list was empty).

Now I put a init flag in the component, so first time that the popup menu is needed, it is updated with the info in the string list, and everything is ok!

Thanks again

A.

Il 18/11/2010 11:38, ha scritto: