[Gambas-user] Problem with OPTIONAL method declaration

[Tobias Boege]

On Wed, 04 Feb 2015, bill-lancaster wrote:
> I have a form with:-
> 
> Public Sub _new(Optional iNr As Integer)   
>      iStatementNr = iNr
> End
> 
> When the form is opened with:-
> 
> Dim hForm As FFormName
>      hForm = New FFormName1019)

Assuming this should read:

  hForm = New FFormName(1019)

>      hForm.ShowModal
> 
> I get this error message - "Type mismatch: wanted control, got integer
> instead"
> 

Form inherits Window and Window has an optional constructor argument (like
every widget): a parent control in which the widget should be created.

As said in the object model document[0], you need to pass the arguments for
all parent classes when you create an object -- and the arguments from the
parent class are always in front of the ones of the child class.

That is, the actual constructor of your FFormName has a signature like

  FFormName._new(Optional Parent As Control, Optional iNr As Integer)

If you want your FFormName object to be an actual window, you can pass a
Null as the Parent argument.

> Wheras just:-
>      FFormName.ShowModal()
> Works OK
> 

This is totally different. You are using the automatic instance[1] of your
FFormName class here which is an object that was already created.

Regards,
Tobi

[0] http://gambaswiki.org/wiki/doc/object-model#t18
[1] http://gambaswiki.org/wiki/lang/createstatic

-- 
"There's an old saying: Don't change anything... ever!" -- Mr. Monk