[Xotcl] NX direct variable access

[Victor Mayevski]

Excellent. Thank you Gustaf.

On Wed, Jan 19, 2011 at 4:50 AM, Gustaf Neumann <neumann at wu.ac.at> wrote:
> Am 19.01.11 10:19, schrieb Victor Mayevski:
>>
>> In NX, what is the correct way to give a direct access to an object
>> variable for outside caller, just like we used to do with XOTcl's
>> [myvar varname]?
>>
> I assume, you want to obtain a fully qualified variable handle for an
> instance variable. Essentially, it works in nx very similar to XOTcl.
> See below for the method "bindvar" which obtains the fully
> qualified name and shows its usage in the context of Tk.
>
> -gustaf neumann
>
> ==================================================
> #
> # Tiny Tk example with bindvar and callback
> #
> # -gustaf neumann
>
> package require nx
> package require Tk
>
> nx::Class create Callbacks {
>  #
>  # A small support class to ease syntactically the reference to
>  # instance variables and the registration of callbacks.
>  #
>  :method bindvar {name} {
>    :require namespace
>    return [nx::self]::$name
>  }
>  :method callback {name args} {
>    return [list [nx::self] $name {*}$args]
>  }
> }
>
> nx::Class create Myclass {
>
>  #
>  # A sample application class that creates a text entry field bound
>  # to an instance variable. When the provided button is pressed, the
>  # content of the variable is placed into an additional output label.
>  #
>
>  :mixin Callbacks
>
>  :public method button-pressed {} {
>    .label configure -text ${:myvar}
>  }
>
>  :method init {} {
>    wm geometry . -500+500
>    pack [label .title -text "Type something and press start button...."]
>    pack [entry .text -textvariable [:bindvar myvar]]
>    pack [label .label]
>    pack [button .button -text start -command [:callback button-pressed]]
>  }
> }
>
> Myclass new
> ==================================================
>
>
> --
> Univ.Prof. Dr. Gustaf Neumann
> Institute of Information Systems and New Media
> WU Vienna
> Augasse 2-6, A-1090 Vienna, AUSTRIA
>
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