From: Jeppe Jakobsen <jeppe88@...>
Date: 2006-04-12T17:41:38+09:00
Subject: Re: Q about tk buttons

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Thanks that kind of worked, but how come that the variable still returns 0,
when I add

puts var.value

to my code, just before Tk.mainloop?

2006/4/12, Hidetoshi NAGAI <nagai@ai.kyutech.ac.jp>:
>
> From: "Jeppe Jakobsen" <jeppe88@gmail.com>
> Subject: Q about tk buttons
> Date: Wed, 12 Apr 2006 06:41:39 +0900
> Message-ID: <99b4ad3b0604111441p38d22688q14e03516af13db40@mail.gmail.com>
> > Why can I use var +=3D 1 outside of the button, when I can't use it ins=
ide
> it.
>
> It means "var =3D var + 1".
> "var + 1" returns 4, because TkVariable#+(obj) method expects
> "numerical plus" when the arguemnt 'obj' is kind of Numeric.
> And by setting the numeric value 4 to var, var losts the link
> to the TkVariable object.
>
> Therefore, for example,
>
> > var =3D TkVariable.new(0) #defining variable
> > var +=3D 1 #making it a fixnum and adding 1
>
> var.value =3D var + 1
>   or
> var.numeric +=3D 1
>
> > root =3D TkRoot.new()
> >
> > label =3D TkLabel.new(:text=3D> var).pack()
>
> label =3D TkLabel.new(:textvariable=3D>var).pack()
>
> > button =3D TkButton.new(:text=3D> "Button", :command=3D>proc{var +=3D 1=
}).pack()
>
> button =3D TkButton.new(:text=3D> "Button", :command=3D>proc{var.value =
=3D var +
> 1}).pack()
>    or
> button =3D TkButton.new(:text=3D> "Button", :command=3D>proc{var.numeric =
+=3D
> 1}).pack()
>
> --
> Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)
>
>
>


--
"winners never quit, quitters never win"

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