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StringList Objects

Posted on 1998-10-16
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Last Modified: 2013-11-23
I am interested in using the Objects property of a StringList to associate objects with certain Lines of a RichEdit. However, Delphi's help says that certain StringList objects ignore the Object property because "they don't make sense, like Lines in a Memo". I'm not sure exactly what that means but is there a way to associate Objects with Lines in a memo (or richedit) object?
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Question by:jcglen
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by:jcglen
ID: 1343156
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rwilson032697 earned 50 total points
ID: 1343157
What the help is saying is that the designers of the TMemo (and probably TRichEdit) objects couldn't think of a reason to do it and so didn't.

The easiest way is to have a TList that stores the objects. You could match the index of a line of text in the lines property to the index of an object in the TList object.

You will need to manage what happens when the user deletes/adds lines etc whch may be a little awkward, but if it is to be read-only this should be fine...

Cheers,

Raymond.
 
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by:Edo082297
ID: 1343158
Hello jcglen
   Associating line indexes with TList pointers is not a good idea in my opinion. I use the Objects member (or related Data member in TListItems) a lot because they are very useful. There are two ways to do what you are trying to do. First of all, since the Lines property of a TRichEdit is itself of type TStrings, you could associate your object with Lines.Objects. The second more complicated thing keeps your objects associated with your string list (which is what you want to do, right?).

First, declare a small class, called TLine:

  TLine = class
  private
    FLine : String;
  end;

Now, to associate a given line with your object, create an object of type TLine and associate it with your string list member.

  MyLine := TLine.Create;
  MyLine.FLine := RichEdit1.Lines[y];
  MyStringList.Objects[x] := MyLine;

Now you have kept the text in your string list and have an associated object. You can dereference the string like this:
 
  TLine(MyStringList.Objects[AnIndex]).FLine;

You can also search your stringlist using IndexOf, IndexOfObject, and so on (just like you can with Lines). The Objects and Data members of various classes in Delphi are very powerful in this regard.

Finally, in your destructor, you have to free the memory you have allocated for each of these objects. Do the following:

  for i := 0 to Pred(MyStringList.Count) do
    TLine(MyStringList.Objects[x]).Free;

Regards,
Edo

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Expert Comment

by:Edo082297
ID: 1343159
I am tired, there is a mistake in the destructor, [x] should read [i].

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