I would like to add some extra fields to TListColumn, but TListColumns
creates only items of class TListColum.
Can someone help me on this one, please?

In article <knE%7.38$235.9...@news.chello.be>, "Drakkar"

What do you mean by "extra fields" - do you mean extra columns.

Each Item[] of a TListView has SubItems (which is a TStrings). Each String of
the SubItems is placed in the corresponding TListColumn of the TListColumnS.

To show an extra column of data you have to add a String to the SubItems and
(if there are then more SubItems than Columns) add a TListColumn to the
TListColumnS.

TListColumnS/TListColumn are an implementation of descendants of a
TCollection/TCollecftionItem.

Alan Lloyd
alangll...@aol.com

By extra fields I mean to extend the TListColum object with extra properties
(eg datatype, ....)

news:20020112022321.07101.00001177@mb-mn.aol.com...

In article <9OU%7.81$oE6.8...@news.chello.be>, "Drakkar"

Could you not create descendants of TListColumnS and TListColumn (the latter
with your additional fields) and allocate the instance of TListColumnS
descendant to the ListView.Columns.

Alan Lloyd
alangll...@aol.com

How do you add the descendants of TListColumn to TListColumS ?  Normally the
result of TListColums.Add is a TListColumn.

news:20020112101347.01395.00001369@mb-cp.aol.com...

With Add.

TCollection has a virtual class method that is used by
Add to get the type to instantiate new items from.
TListColumns overrides it to return TListColumn; the
class derived from TListColumns would override it to
return the class derived from TListColumn. Add itself
is static, but it uses a virtual method, so it _will_
adapt its behaviour in a new subclass.

(Read the source to TCollection if you have it.)

Groetjes,
Maarten Wiltink

In article <sPE08.369$503.12...@news.chello.be>, "Drakkar"

No - what I said (or thought I said <g>) was ...

TMyListColumnS = class(TListColumnS)
   etc etc

TMyListColumn := class(TListColumn)
  etc etc

 MyListColumnS := TMyListColumns.Create(TMyListColumn);
 MyListView.Columns := MyListColumnS;

Perhaps you don't even have to do that ...

Perhaps you can just say ...

 MyListColumnS := TListColumnS.Create(TMyListColumns);
 MyListView.Columns := MyListColumnS;

... or perhaps it won't work that way at all <g>

Alan Lloyd
alangll...@aol.com