|
|
| Line 28: |
Line 28: |
| Simply add wininet.lib to your project (file can be found in \lib directory of your C++ Builder / BDS / CRS installation). In recent IDEs you can also add<br> | | Simply add wininet.lib to your project (file can be found in \lib directory of your C++ Builder / BDS / CRS installation). In recent IDEs you can also add<br> |
| <code>#pragma link "wininet.lib"</code><br> in your code. | | <code>#pragma link "wininet.lib"</code><br> in your code. |
|
| |
| ==NG Serialization==
| |
| ===How to serialize collections===
| |
| Serializing collections, including custom or standard collections (like TList) requires writing custom converters. For example, lets consider the folowing collection declaration:
| |
|
| |
| <pre class="brush:delphi">
| |
| type
| |
| TItem = class
| |
| public
| |
| X: Integer;
| |
| Y: Integer;
| |
| end;
| |
|
| |
| TItems = class(TObjectList<TItem>);
| |
| </pre>
| |
|
| |
| To be able to serialize it, we need to declare a converter class, and '''associate''' this class with our collection using Converter attribute:
| |
|
| |
| <pre class="brush:delphi">
| |
| type
| |
| TItemsConverter = class(TConverter)
| |
| public
| |
| function GetReadMode: TReadMode; override;
| |
| procedure Write(S: TSerializer; const V); override;
| |
| procedure Read(D: TDeserializer; var V); override;
| |
| end;
| |
|
| |
| [Converter(TItemsConverter)]
| |
| TItems = class(TObjectList<TItem>);
| |
| </pre>
| |
|
| |
| The converter can be implemented like this:
| |
|
| |
| <pre class="brush:delphi">
| |
| function TItemsConverter.GetReadMode: TReadMode;
| |
| begin
| |
| Result := rmFillRead; // Indicate fill-read mode.
| |
| end;
| |
|
| |
| procedure TItemsConverter.Read(D: TDeserializer; var V);
| |
| var
| |
| lst: TItems;
| |
| begin
| |
| lst := TItems(V); // Since we work in fill-read mode,
| |
| // V already contains a reference to
| |
| // TItems instance; we should not
| |
| // create it here.
| |
| lst.Clear;
| |
|
| |
| D.BeginArray;
| |
| while D.HasNext do
| |
| lst.Add(D.Value<TItem>);
| |
| D.EndArray;
| |
| end;
| |
|
| |
| procedure TItemsConverter.Write(S: TSerializer; const V);
| |
| var
| |
| lst: TItems;
| |
| i: Integer;
| |
| begin
| |
| S.BeginArray;
| |
| lst := TItems(V);
| |
| for i := 0 to lst.Count - 1 do
| |
| S.Value(lst[i]);
| |
| S.EndArray;
| |
| end;
| |
| </pre>
| |
|
| |
| As can be seen, GetReadMode returns rmFillRead, which indicates that de-serializer should use fill-read mode. This means that no new TItems instance is created during de-serialization. This mode is especially usefull for collection like classes, because they usually owned by some other objects. For example, lets look at the following class:
| |
|
| |
| <pre class="brush:delphi">
| |
| type
| |
| TOwner = class
| |
| private
| |
| FItems: TItems;
| |
| public
| |
| constructor Create;
| |
| destructor Destroy; override;
| |
| property Items: TItems read FItems;
| |
| end;
| |
|
| |
| constructor TOwner.Create;
| |
| begin
| |
| inherited Create;
| |
| FItems := TItems.Create;
| |
| end;
| |
|
| |
| destructor TOwner.Destroy;
| |
| begin
| |
| FItems.Free;
| |
| inherited;
| |
| end;
| |
| </pre>
| |
|
| |
| As can be seen, TItems collection is oqned by TOwner class. TOwner expose Items as read-only property, and thus, there no way to replace collection as a whole. Only collection content can be changed.
| |
|
| |
| But, fortunately, TOwner class can be serialized and de-serialized, because TItems collection has fill-read mode converter:
| |
|
| |
| <pre class="brush:delphi">
| |
| var
| |
| src, dst: TOwner;
| |
| stream: TStream;
| |
| s: TBinarySerializer;
| |
| d: TBinaryDeserializer;
| |
| begin
| |
| stream := TMemoryStream.Create;
| |
| try
| |
| src := TOwner.Create;
| |
| src.Items.Add(TItem.Create);
| |
| src.Items.Add(TItem.Create);
| |
| src.Items.Add(TItem.Create);
| |
|
| |
| s := TBinarySerializer.Create(stream);
| |
| s.Value(src);
| |
| s.Free;
| |
|
| |
| stream.Position := 0;
| |
|
| |
| d := TBinaryDeserializer.Create(stream);
| |
| dst := d.Value<TOwner>;
| |
| d.Free;
| |
| finally
| |
| stream.Free;
| |
| end;
| |
| end;
| |
| </pre>
| |
|
| |
| Please use the following link for more information about fill-read mode:
| |
| [http://www.lmd.de/downloads/tutorials/serialization/index.html?fill-read_mode.htm Fill-Read Mode]
| |
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Please check list of different RichEdit versions.
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LMD WebPack
[Linker Error] Unresolved external "InternetCloseHandle" referenced from
Simply add wininet.lib to your project (file can be found in \lib directory of your C++ Builder / BDS / CRS installation). In recent IDEs you can also add
#pragma link "wininet.lib"
in your code.