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Re: Best Way to Pass Info Between Objects?

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On 01/08/2012 11:41 AM, Novice wrote:
> Sorry, that's probably not the best of subject lines but I'm having trouble
> coming up with a concise one....
>
> I'm trying to reason out the best way to pass information from an
> instantiating class to an instantiated class. So, let's say class Foo
> invokes class Bar to do something. Bar needs some specific information from
> Foo to do its job. What is the best way to pass this information from Foo
> to Bar?
>
> For instance, Foo is a class that is used to edit a table of information
> presented as a JTable. Bar is a class that is used when a new row needs to
> be inserted into the table. The person using Foo right-clicks, chooses
> "Insert" on the context menu, and Bar gets instantiated to display a dialog
> with input fields so that the user can supply the values for a new row of
> the JTable.
>
> Bar needs various things to do its job. Among these are:
> - the locale to be used since Bar can display its text in various languages
> - the logger to be used for error messages
> - a reference to Foo since Bar wants to know the parent JFrame
> - the title of the dialog
>
> There are obviously various techniques for passing information from Foo to
> Bar. You can put the information in the paramater list. You can use getters
> to obtain the information from Foo. You can make values in Foo accessible
> to Bar by making the public so that Bar can access them directly. All of
> these methods can and do get used in Java.
>
> What are the rules of thumb to use in deciding which techniques to use in
> any given case?
>
> Clearly parameter passing is used widely but parameter lists tend to be
> short, mostly in the 0 to 4 parameter range. How do you decide which of the
> possibly many things needed by class Bar get passed as parameters and which
> get passed via getters or accessed directly from Foo?
>
> My strong impression is that it's bad form to access variables directly in
> Foo and that getters are preferred, but please correct me if I'm wrong. But
> I still don't quite see when you prefer passing something in a parameter
> list rather than via a getter.
>
> I'm not sure if there is a generally agreed-upon formula here or whether it
> is more a case of individual style and preference. I'd be very interested
> in your comments on this subject. Right now, I feel like I'm being pretty
> inconsistent in my techniques and would like to standardize them along the
> best possible lines.
>
 From your posts asking for help with your table, one thing hasn’t 
become clear to me. What about your 'information'? Surely the be-all and 
end-all of your information is not display in a table. Who uses the 
information, where do you store it, how do you access it? If you are 
very clear on the structure and use of your information the CRUD will be 
much easier to visualize.

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Best Way to Pass Info Between Objects? Novice <novice@example..com> - 2012-01-08 16:41 +0000
  Re: Best Way to Pass Info Between Objects? Patricia Shanahan <pats@acm.org> - 2012-01-08 09:08 -0800
    Re: Best Way to Pass Info Between Objects? Novice <novice@example..com> - 2012-01-08 18:22 +0000
      Re: Best Way to Pass Info Between Objects? markspace <-@.> - 2012-01-08 10:45 -0800
      Re: Best Way to Pass Info Between Objects? Lew <noone@lewscanon.com> - 2012-01-08 11:49 -0800
      Re: Best Way to Pass Info Between Objects? Patricia Shanahan <pats@acm.org> - 2012-01-08 14:04 -0800
        Re: Best Way to Pass Info Between Objects? Martin Gregorie <martin@address-in-sig.invalid> - 2012-01-08 22:40 +0000
          Re: Best Way to Pass Info Between Objects? Patricia Shanahan <pats@acm.org> - 2012-01-08 15:56 -0800
            Re: Best Way to Pass Info Between Objects? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-01-09 06:34 -0400
              Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-09 12:39 -0500
                Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-09 12:42 -0500
                Re: Best Way to Pass Info Between Objects? Lew <lewbloch@gmail.com> - 2012-01-09 13:43 -0800
                Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-09 17:26 -0500
                Re: Best Way to Pass Info Between Objects? Lew <noone@lewscanon.com> - 2012-01-10 06:47 -0800
                Re: Best Way to Pass Info Between Objects? Patricia Shanahan <pats@acm.org> - 2012-01-09 14:26 -0800
                Re: Best Way to Pass Info Between Objects? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-01-09 19:06 -0400
                Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-09 18:46 -0500
                Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-09 19:52 -0500
                Re: Best Way to Pass Info Between Objects? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-01-10 06:43 -0400
              Re: Best Way to Pass Info Between Objects? Martin Gregorie <martin@address-in-sig.invalid> - 2012-01-10 02:11 +0000
              Re: Best Way to Pass Info Between Objects? Gene Wirchenko <genew@ocis.net> - 2012-01-09 20:17 -0800
              Re: Best Way to Pass Info Between Objects? Lew <noone@lewscanon.com> - 2012-01-10 06:43 -0800
                Re: Best Way to Pass Info Between Objects? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-01-10 19:13 -0400
      Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-09 14:30 -0500
        Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-09 17:28 -0500
          Re: Best Way to Pass Info Between Objects? Martin Gregorie <martin@address-in-sig.invalid> - 2012-01-10 02:24 +0000
            Re: Best Way to Pass Info Between Objects? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-01-10 06:35 -0400
              Re: Best Way to Pass Info Between Objects? Martin Gregorie <martin@address-in-sig.invalid> - 2012-01-10 22:48 +0000
  Re: Best Way to Pass Info Between Objects? v_borchert@despammed.com (Volker Borchert) - 2012-01-08 17:17 +0000
  Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-08 13:43 -0500
    Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-08 19:01 -0500
  Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-08 14:10 -0500
    Re: Best Way to Pass Info Between Objects? Jeff Higgins <jeff@invalid.invalid> - 2012-01-08 14:41 -0500
  Re: Best Way to Pass Info Between Objects? Roedy Green <see_website@mindprod.com.invalid> - 2012-01-09 04:13 -0800

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