Newbie Question - How to reference widgets in GUI Application.

[dciphercomputing]

Hi

On a form I want to display the name of the widget the pointer enters.  This is purely a learning exercise because I want to learn about how events work in Eiffel and I want to learn how to reference widgets etc.

So how do I reference widgets in code?  Is there a "this" or "self" keyword to start the reference such as this.parent.my_container.my_textbox.caption?

I am also interested in finding some sample code showing how events are added in code once you build the GUI with EiffelBuild.

Thanks,
Simon

[Colin LeMahieu]

Current is the Eiffel equivalent to "this"

On Fri, Sep 11, 2009 at 12:10 PM, dciphercomputing <
[hidden email]> wrote:

>
>
> Hi
>
> On a form I want to display the name of the widget the pointer enters. This
> is purely a learning exercise because I want to learn about how events work
> in Eiffel and I want to learn how to reference widgets etc.
>
> So how do I reference widgets in code? Is there a "this" or "self" keyword
> to start the reference such as this.parent.my_container.my_textbox.caption?
>
> I am also interested in finding some sample code showing how events are
> added in code once you build the GUI with EiffelBuild.
>
> Thanks,
> Simon
>
>  
>

[Non-text portions of this message have been removed]

[Peter Gummer-2]

Colin LeMahieu wrote:

> Current is the Eiffel equivalent to "this"

True, but you would not write 'Current.tools_menu' to reference the  
window's Tools menu. You would simply write:

        tools_menu

It is extremely rare in Eiffel to mention 'Current' explicitly as the  
target of call. The same is true in many other languages, actually; in  
C#, for example, I would never write 'this.ToolsMenu', except in the  
very rare case where there might be ambiguity; I would simply write  
'ToolsMenu'. Because Eiffel's language rules prevent any such  
ambiguity, you almost never see anyone write 'Current' followed by a  
dot.

- Peter Gummer

[dciphercomputing]

Does this mean that ever widget no matter how deep in the heirarchy can simply be referenced by its name?  So if this is true I then I assume I can stop thinking in terms of an object heirarchy when trying to reference widgets.

Simon

--- In [hidden email], Peter Gummer <p-gummer@...> wrote:

>
> Colin LeMahieu wrote:
>
> > Current is the Eiffel equivalent to "this"
>
> True, but you would not write 'Current.tools_menu' to reference the  
> window's Tools menu. You would simply write:
>
> tools_menu
>
> It is extremely rare in Eiffel to mention 'Current' explicitly as the  
> target of call. The same is true in many other languages, actually; in  
> C#, for example, I would never write 'this.ToolsMenu', except in the  
> very rare case where there might be ambiguity; I would simply write  
> 'ToolsMenu'. Because Eiffel's language rules prevent any such  
> ambiguity, you almost never see anyone write 'Current' followed by a  
> dot.
>
> - Peter Gummer
>

[Peter Gummer-2]

dciphercomputing wrote:

> Does this mean that ever widget no matter how deep in the heirarchy  
> can simply be referenced by its name?

Yes. that's right. The same as any other object-oriented language (or  
at least the ones that I know).

- Peter Gummer