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Re: Fwd: Re: PROP_TYPE_LIST declaration [lrclause cs uiuc edu]

Note that if your list is static, you may want to use PROP_TYPE_ENUM.  I
think it's prettier and easier to deal with (though I may end up changing
the PROP_TYPE_LIST widget (or even removing it -- there's not much
difference between the two, all PROP_TYPE_LIST seems to have going for it
is that it uses GPtrArray)).


It's dynamic.  Functionally quite similar to attributes in the UML (although I know the UML objects still 
probably don't make use of StdProp yet).  Should I avoid PROP_TYPE_LIST if you're considering removing it?


You need to declare the index within your structure as well:

   GPtrArray *column_list;    /* The list of items */
   int column_list_index;       /* The currently selected item */

To declare a ListProp in the PropOffset array, you give it the offset of
both the list and the index:

  { "column_list", PROP_TYPE_LIST, offsetof(Independent, column_list),
                                   offsetof(Independent, column_list_index) },


And there are no name and flags fields?  Looking at chronoline.c and what you have above, the maximalist in 
me wants to do something like:

   { "column_list", PROP_TYPE_LIST, PROP_FLAG_VISIBLE,
     N_("Column list"), offsetof(Independent, column_list),
     N_("Column index"), offsetof(Independent, column_list_index), NULL },

Also, the quoted example leads to a GCC warning about the column_list_index parameter in offsetof(), which 
worries me:

independent.c:156: warning: initialization makes pointer from integer without a cast

Thanks,
Andy
--- Begin Message --- 
On Thu, 10 Apr 2003, ashalper cox net wrote:

I was wondering if someone could help me out with a PROP_TYPE_LIST
declaration (I couldn't find any examples in the CVS code). 


There aren't any, in fact.

Note that if your list is static, you may want to use PROP_TYPE_ENUM.  I
think it's prettier and easier to deal with (though I may end up changing
the PROP_TYPE_LIST widget (or even removing it -- there's not much
difference between the two, all PROP_TYPE_LIST seems to have going for it
is that it uses GPtrArray)).


I think I've got my PropDescription struct correct, but I need help on
the offsets and the declaration in my object struct.  The PROP_TYPE_LIST
macro in properties.h is:

#define PROP_TYPE_LIST "list"  /* ListProperty */
/* (offset is a GPtrArray of (const gchar *). offset2 is a gint, index of the 
   active item, -1 if none active.) */

My object struct looks something like:

typedef struct _Independent {
  Element element;

  GPtrArray *column_list;     /* the ListProperty? */
     .
     .
     .

} Independent;

but I'm missing the index, and I'm not at all sure how to declare the
PropOffset array correctly.


You need to declare the index within your structure as well:

   GPtrArray *column_list;      /* The list of items */
   int column_list_index;       /* The currently selected item */

To declare a ListProp in the PropOffset array, you give it the offset of
both the list and the index:

  { "column_list", PROP_TYPE_LIST, offsetof(Independent, column_list),
                                   offsetof(Independent, column_list_index) },

Remember to create the GPtrArray when you create the array, and set the
index to something reasonable (-1 for no initial selection).  You may also
need to do a deep copy of the list when the object gets copied.

-Lars

-- 
Lars Clausen (http://shasta.cs.uiuc.edu/~lrclause)| HÃrdgrim of Numenor
"I do not agree with a word that you say, but I   |----------------------------
will defend to the death your right to say it."   | Where are we going, and
    --Evelyn Beatrice Hall paraphrasing Voltaire  | what's with the handbasket?
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