Author: Tomas Rutkauskas

I have written a component which uses TCollections as properties. Now I need a way 
to save the TCollectionItems to a file. How can I do that?

Answer:

You may try these routines. I have tested them with TStatusBar.Panels collection 
and they worked for me:
1   
2   procedure LoadCollectionFromStream(Stream: TStream; Collection: TCollection);
3   begin
4     with TReader.Create(Stream, 4096) do
5     try
6       CheckValue(vaCollection);
7       ReadCollection(Collection);
8     finally
9       Free;
10    end;
11  end;
12  
13  procedure LoadCollectionFromFile(const FileName: string; Collection: TCollection);
14  var
15    FS: TFileStream;
16  begin
17    FS := TFileStream.Create(FileName, fmOpenRead or fmShareDenyWrite);
18    try
19      LoadCollectionFromStream(FS, Collection);
20    finally
21      FS.Free;
22    end;
23  end;
24  
25  procedure SaveCollectionToStream(Collection: TCollection; Stream: TStream);
26  begin
27    with TWriter.Create(Stream, 4096) do
28    try
29      WriteCollection(Collection);
30    finally
31      Free;
32    end;
33  end;
34  
35  procedure SaveCollectionToFile(Collection: TCollection; const FileName: string);
36  var
37    FS: TFileStream;
38  begin
39    FS := TFileStream.Create(FileName, fmCreate or fmShareDenyWrite);
40    try
41      SaveCollectionToStream(Collection, FS);
42    finally
43      FS.Free;
44    end;
45  end;


Note: It's obvious, the Collection variable must point to the initialized instance 
of a TCollection
descendant.