Re: GUI questions

[Ben Pfaff]

John Darrington <address@hidden> writes:

> On Mon, Oct 01, 2007 at 10:10:29PM -0700, Ben Pfaff wrote:
>
>      The reason I left out Z-scores from my initial DESCRIPTIVES
>      dialog design was that I didn't think that they made any logical
>      sense there.  It seems to be that they should be on the Transform
>      menu, or at least in a separate "Compute Z-Scores" menu item
>      under Analyze|Descriptive Statistics.  They're only a part of the
>      DESCRIPTIVES procedure because it's convenient to put them there,
>      not because it makes a lot of sense from a UI perspective.  But
>      moving them to a new menu item could also confuse users who
>      expect them to be in the old place.
>
> OK.  I'm not sure how often it will be used anyway.  I think for now,
> this could be left unimplemented.  Let's wait until somebody complains
> about its absence.

I should have noted that in fact I already implemented the
Z-scores checkbox in my working directory.

My thoughts on a GUI are not hardened into dogma.

> Recently I've been thinking the same as yourself;  psppire.glade
> should be split up into seperate files.

OK.

>      For
>      examples, procedures can't run without any data, so should we
>      gray out the Analyze menu until there's data?  
>
> I think not.  Procedures can run without data, although in most cases
> they will give trivial (and perhaps meaningless) answers.

How about if there are no variables?

>      specific procedures have more stringent requirements; for
>      example, DESCRIPTIVES needs at least one numeric variable,
>      CROSSTABS needs at least two variables (for any sensible
>      results), and so on.  Should that be implemented by graying out
>      menu items, by displaying an error dialog if the menu item is
>      selected, or another way?
>
> A "good" GUI should prevent the user from choosing invalid options.
>
> If a procedure requires only numeric variables (or variables
> satisfying any other predicate), then you can enforce that by only
> displaying the appropriate variables in the treeview (use the last
> argument of attach_dictionary_to_treeview).  See the weight cases
> dialog for an example of this.

I did that.  But I was thinking of the case where there are no
numeric variables at all in the active file dictionary.  Does the
answer change in that case?

> Currently, I don't think there's any way to deal with the situation
> where there are two fields in the same dialog which have different
> constraints on what properties a variable may have.

OK.

>      Finally, there are constraints on what
>      can be selected in a procedure before it can be invoked; e.g. for
>      DESCRIPTIVES it's necessary to select at least one variable
>      before clicking on Paste or OK.  How should this be enforced?
>
> Paste and OK should be greyed ("insensitive" in GTK+ terminology)
> until the dialog has been set up so that sensible things happen when
> you click them.

OK.

> This is an issue not only for DESCRIPTIVES, but for nearly all the
> dialogs, and I haven't addressed it yet.  Probably I should add a
> method on the PsppireButtonBox widgets.   I was going to wait until
> after 0.6.0 before looking at that.  Do you think it's more urgent?

No, it's not a big deal.
-- 
Ben Pfaff 
http://benpfaff.org