Ruby tkentry tkvariable with class wrappers problem

Ruby
1

I try to create a tkEntry with a tkVariable attached in the class
startupinterface and create a callback to startupinterfacecontroller but
it doesn’t work : it says that themember variable supposed to hold a
link to the tkVariable object is nil:nilClass when i try to call the
value member function

code is in attachement

any help appreciated

2

From: Cristian A. [email protected]
Subject: ruby tkentry tkvariable with class wrappers problem
Date: Tue, 24 Mar 2009 04:43:01 +0900
Message-ID: [email protected]

it doesn’t work : it says that themember variable supposed to hold a
link to the tkVariable object is nil:nilClass when i try to call the
value member function

Hmmm…
You may be misunderstanding about a block given to .new.

And, your code has a problem about accessing a TkVariable object.

@files_lcoation_text=TkVariable.new
@files_location_text=“”
@files_location_entry=TkEntry.new(tk_root){
textvariable @files_location_text
}.grid(“row”=>0 , “column”=>1)
@files_location_text=“tada”

Such block is evaluated with “instance_eval”.
That is, at internal of the block, “self” is the widget created by
“new” method. So, @files_location_text in the block is a instance
variable of the entry widget.

There are two ways to avoid this problem.
The one is to use a local variable.
And another is to use a Hash argument.

-----<case.1>----------------------------------------------
@files_lcoation_text = txt_var = TkVariable.new(“”)
@files_location_entry=TkEntry.new(tk_root){
textvariable txt_var
}.grid(“row”=>0 , “column”=>1)
@files_location_text.value = “tada”

-----<case.2>----------------------------------------------
@files_lcoation_text = TkVariable.new(“”)
@files_location_entry=TkEntry.new(tk_root,
:textvariable=>@files_lcoation_text).grid(:row=>0 , :column=>1)
@files_location_text.value = “tada”

Please take attention to a scope of a variable.

3

problem solved ; thanks for the help

4

the fix is good but i hit another problem

when I try to change the value of the tkvariable member variable with
the value member function of tkvariable it doesn’t work : it says
nil:NilClass when pressing the button change_entry_text

I try to change the value of the initial entry/tkvariable by using the
value of a new one or possibly the value supplied by any external class
that has a reference

new code version is attached

5

that fixed it again hope i’ll be more carefull next time and not post
typo questions

6

From: Cristian A. [email protected]
Subject: Re: ruby tkentry tkvariable with class wrappers problem
Date: Tue, 24 Mar 2009 07:00:24 +0900
Message-ID: [email protected]

when I try to change the value of the tkvariable member variable with
the value member function of tkvariable it doesn’t work : it says
nil:NilClass when pressing the button change_entry_text

It’s a typo.

— chess_games_helper.rb.orig 2009-03-24 11:38:46.000000000 +0900
+++ chess_games_helper.rb 2009-03-24 11:40:03.000000000 +0900
@@ -51,7 +51,7 @@
files_location_entry_d.insert(‘end’ , “data files
location”)
files_location_entry_d.state=“disabled”

  •           @files_lcoation_text=txt_var=TkVariable.new

  •           @files_location_text=txt_var=TkVariable.new

          new_txt=TkVariable.new
          files_location_entry=TkEntry.new(tk_root){