[Gambas-user] dynamic created Menus

[Gianluigi]

Hi Tobias,
I thank you a lot for explanations, in fact I was too concise because, but
not only, of my English.
One thing, when you say: "You can still create objects from a module but
that
isn't useful because you don't have dynamic symbols in a module", what
exactly do you mean by "symbols", because in a module we can insert
dynamics variables, functions, sub etc.

Regards
Gianluigi

2017-02-15 13:47 GMT+01:00 Tobias Boege <taboege at ...626...>:

> On Wed, 15 Feb 2017, Gianluigi wrote:
> > Hi Fabien,
> > let's see if I can clarify this.
> > In Gambas there are three different types of class:
> > - The real Class and its to be instantiated through the constructor
> (_new).
> > - The Form which is a class already instantiated, but can receive the
> > parameters which exposes the constructor (_new).
> > - The Module is a class already instantiated, and that does not expose
> the
> > constructor.
> >
> > Therefore I can refer to a module with Me, I can use inside events and I
> > can even assign _new with another name to the module even if do not
> really
> > need.
> > I'm on the right track?
> >
>
> This is not how I would understand the matter. First of all, you have your
> normal classes in Gambas. You can alter their behaviour by setting certain
> "flags" in your class. These flags are actually keywords in the Gambas
> language and you have to specify them at the beginning of your class file
> at compile time.
>
>   o CREATE PRIVATE tells the interpreter that the current class is not
>     instanciable.
>   o CREATE STATIC tells the interpreter to create an automatic instance of
>     the class which is used automatically when you use the class name like
>     an object.
>
> There is also EXPORT and INHERITS, but they're of minor relevance for the
> topic at hand.
>
> None of these flags influence the presence of ME or events. They are always
> available.
>
> Now, a module is a normal class in which every symbol is implicitly made
> static by the compiler. You can still create objects from a module but that
> isn't useful because you don't have dynamic symbols in a module. You will
> just end up with multiple objects that all reference the same data.
>
> The only way the Form class is any special is because it has dedicated
> support for .form files in the compiler. Other than that it is a normal
> class -- which uses the CREATE STATIC flag. Quoting the definition of the
> Form class from gb.qt4/src/CWindow.cpp:
>
> 1466 GB_DESC CFormDesc[] =
> 1467 {
> 1468         GB_DECLARE("Form", sizeof(CFORM)), GB_INHERITS("Window"),
> 1469         GB_AUTO_CREATABLE(),
> 1470
> 1471         GB_STATIC_METHOD("Main", NULL, CFORM_main, NULL),
> 1472         GB_STATIC_METHOD("Load", NULL, CFORM_load,
> "[(Parent)Control;]"),
> 1473         GB_METHOD("_new", NULL, CFORM_new, NULL),
> 1474
> 1475         FORM_DESCRIPTION,
> 1476
> 1477         GB_END_DECLARE
> 1478 };
>
> The macro GB_AUTO_CREATABLE() is the C rendition of CREATE STATIC. As you
> can see, Form just inherits Window and adds three further methods. These
> methods are actually what makes Form classes behave the special way they
> do, like automatically showing on program startup and being their own event
> observers. (And, well, there's the FORM_DESCRIPTION macro but don't worry
> about it.) My point is, the behaviour of a Form is accomplished by standard
> Gambas mechanisms, that are available to everyone (only the conversion of
> .form files to executable code needs specific support in the compiler).
>
> Regards,
> Tobi
>
> --
> "There's an old saying: Don't change anything... ever!" -- Mr. Monk
>
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