|
1 <?xml version="1.0" encoding="utf-8"?> |
|
2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
|
3 <!-- This component and the accompanying materials are made available under the terms of the License |
|
4 "Eclipse Public License v1.0" which accompanies this distribution, |
|
5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
|
6 <!-- Initial Contributors: |
|
7 Nokia Corporation - initial contribution. |
|
8 Contributors: |
|
9 --> |
|
10 <!DOCTYPE concept |
|
11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
|
12 <concept id="GUID-772DFFA1-4BBC-516F-909D-47CB773760F5" xml:lang="en"><title>Packages |
|
13 as type-safe descriptors</title><shortdesc>Describes the package function to transfer data in correct structure. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody> |
|
14 <p>Descriptors are often used as the basis of data transfer within Symbian |
|
15 platform. For example, inter-thread data transfer is specified in terms of |
|
16 transferring data from a descriptor valid in the context of one thread, to |
|
17 a descriptor valid in the context of another.</p> |
|
18 <p>Data to be transferred almost always has a well defined structure and it |
|
19 is important that the receiver of the data has some guarantee that the correct |
|
20 structure has been passed. This is type safety.</p> |
|
21 <p>A package <i>is</i> a descriptor and also acts as a wrapper around it. |
|
22 It allows objects and data structures to be represented by descriptors in |
|
23 a type safe way. Objects are either contained within a modifiable buffer descriptor |
|
24 or are represented by pointer descriptors.</p> |
|
25 <p>A package class is templated, the template parameter being the type of |
|
26 the object represented. The use of a template provides the required type safety.</p> |
|
27 </conbody><related-links> |
|
28 <link> |
|
29 <desc><xref href="GUID-79BAF19D-F003-5468-9C01-6E918B06C36D.dita">Descriptor concepts</xref></desc> |
|
30 </link> |
|
31 </related-links></concept> |