# Ruby tkentry tkvariable with class wrappers problem **URL:** \ **Category:** Ruby\ **Created:** [March 23, 2009, 8:46pm UTC](https://www.ruby-forum.com/t/ruby-tkentry-tkvariable-with-class-wrappers-problem/163673 "2009-03-23T20:46:04Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![branco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/5e9695/32.png) [@branco](https://www.ruby-forum.com/u/branco)\ **Post date:** [March 23, 2009, 8:46pm UTC](https://www.ruby-forum.com/t/ruby-tkentry-tkvariable-with-class-wrappers-problem/163673/1 "2009-03-23T20:46:04Z")
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 ---
**Author:** ![branco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/5e9695/32.png) [@branco](https://www.ruby-forum.com/u/branco)\ **Post date:** [March 23, 2009, 9:21pm UTC](https://www.ruby-forum.com/t/ruby-tkentry-tkvariable-with-class-wrappers-problem/163673/2 "2009-03-23T21:21:26Z")
From: Cristian A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Subject: ruby tkentry tkvariable with class wrappers problem Date: Tue, 24 Mar 2009 04:43:01 +0900 Message-ID: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > 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. ## -----\---------------------------------------------- @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” ## -----\---------------------------------------------- @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. ---
**Author:** ![branco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/5e9695/32.png) [@branco](https://www.ruby-forum.com/u/branco)\ **Post date:** [March 23, 2009, 10:07pm UTC](https://www.ruby-forum.com/t/ruby-tkentry-tkvariable-with-class-wrappers-problem/163673/3 "2009-03-23T22:07:45Z")
problem solved ; thanks for the help ---
**Author:** ![branco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/5e9695/32.png) [@branco](https://www.ruby-forum.com/u/branco)\ **Post date:** [March 23, 2009, 11:03pm UTC](https://www.ruby-forum.com/t/ruby-tkentry-tkvariable-with-class-wrappers-problem/163673/4 "2009-03-23T23:03:26Z")
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 ---
**Author:** ![branco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/5e9695/32.png) [@branco](https://www.ruby-forum.com/u/branco)\ **Post date:** [March 24, 2009, 4:30am UTC](https://www.ruby-forum.com/t/ruby-tkentry-tkvariable-with-class-wrappers-problem/163673/5 "2009-03-24T04:30:24Z")
that fixed it again hope i’ll be more carefull next time and not post typo questions ---
**Author:** ![branco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/5e9695/32.png) [@branco](https://www.ruby-forum.com/u/branco)\ **Post date:** [March 24, 2009, 3:42am UTC](https://www.ruby-forum.com/t/ruby-tkentry-tkvariable-with-class-wrappers-problem/163673/6 "2009-03-24T03:42:06Z")
From: Cristian A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Subject: Re: ruby tkentry tkvariable with class wrappers problem Date: Tue, 24 Mar 2009 07:00:24 +0900 Message-ID: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > 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){ ```