Accesing Values From One Form on Another - forms

Question

Im trying to build in a language switch into one of my programs.
Where the user selects a language and in runtime the app gets translated. I sort of got this working in a small test project. BUT only when the forms are auto created, which i dont want.
the way the forms get created is the following:
SideNote: Most of my forms are fsMDIChild forms.
ParametersForm := TParametersForm.Create(Self); //(consider this the mainform for now)
On ParametersForm I have
procedure TParametersForm.FormCreate(Sender: TObject);
begin
ResourceStringsDM.ParametersF; //(consider this the second form)
end;
this Datamodule houses the captions for ParametersForm.
procedure TResourceStringsDM.ParametersF;
begin
with ParametersForm do
begin
bsSkinLabel1.Caption := 'Execute Nieuwefacturen';
bsSkinLabel2.Caption := 'Execute Viewfacturen';
end;
end;
I have added ResourceStringsDM to the implementation uses of ParametersForm and ParametersForm to the interface uses of ResourceStringsDM.
This all above gives me an access violation cause in the procedure where it sets the captions uses ParametersForm (var name of the form i want to translate) but at that moment this var is nil. Prolly cause it isnt done creating the form yet and hasnt filled in the form var.
The only way i got this all working was by using
Application.CreateForm(TParametersForm, ParametersForm);
But I want to avoid this after reading about it, and that you should only use this on your mainform. Also it doesnt handle passing parameters very well.
Does anyone of you fine people have any hints or tips / help to get me access to the captions of form 1 from form 2?
i probably forgot tons of info you guys need. just tell me and ill add it in.

Answer 1

In an "MDI Application" template (file->new-other->...>, neither MDI childs are auto created nor the child form's unit contains the global form reference. There's a reason for this, more than one instance of a child form should be able to run at the same time. When you have two instances of the same child for instance, which one will the form reference hold?
Anyway, it is of course possible to not to use this design, but then if you don't use the construct you mention in the question, you're responsible for assigning the instance to the reference yourself. So either do it (which I don't recommend):
procedure TParametersForm.FormCreate(Sender: TObject);
begin
ParametersForm := Self;
ResourceStringsDM.ParametersF; //(consider this the second form)
end;
or better, pass the instance to the function in your data module so that it can work on it:
procedure TResourceStringsDM.ParametersF(ParametersForm: TParametersForm);
begin
with ParametersForm do
begin
bsSkinLabel1.Caption := 'Execute Nieuwefacturen';
...
 
procedure TParametersForm.FormCreate(Sender: TObject);
begin
ResourceStringsDM.ParametersF(Self); //(consider this the second form)
end;