学步园

呵呵，下面是一段拨号代码（摘自Nokia的例子），代码虽然不多，但很多地方都值得学习，例如：对R类的使用，清理；server/client机制；参数传递机制；编码风格；注释风格等等自己体会吧。

 在阅读代码之前请熟悉Symbian OS C++中的ETel结构，以及它的核心类RTelServer,RPhone,RLine,RCall.

下面是代码内容：

 void DialNumberL(const TDesC& aPhoneNumber)

{

//Create a connection to the tel server
 RTelServer server;
 CleanupClosePushL(server);
 User::LeaveIfError(server.Connect());

 //Load in the phone device driver
 User::LeaveIfError(server.LoadPhoneModule(KTsyName));
 
 //Find the number of phones available from the tel server
 TInt numberPhones;
 User::LeaveIfError(server.EnumeratePhones(numberPhones));

 //Check there are available phones
 if (numberPhones < 1)
  {
  User::Leave(KErrNotFound);
  }

 //Get info about the first available phone
 RTelServer::TPhoneInfo info;
 User::LeaveIfError(server.GetPhoneInfo(0, info));

 //Use this info to open a connection to the phone, the phone is identified by its name
 RPhone phone;
 CleanupClosePushL(phone);
 User::LeaveIfError(phone.Open(server, info.iName));

 //Get info about the first line from the phone
 RPhone::TLineInfo lineInfo;
 User::LeaveIfError(phone.GetLineInfo(0, lineInfo));

 //Use this to open a line
 RLine line;
 CleanupClosePushL(line);
 User::LeaveIfError(line.Open(phone, lineInfo.iName));

 //Open a new call on this line
 TBuf <100> newCallName;
 RCall call;
 CleanupClosePushL(call);
 User::LeaveIfError(call.OpenNewCall(line, newCallName));

 //newCallName will now contain the name of the call
 User::LeaveIfError(call.Dial(aPhoneNumber));

 //Close the phone, line and call connections and remove them from the cleanup stack
 //NOTE: This does not hang up the call
 CleanupStack::PopAndDestroy(3);//phone, line, call

 //Unload the phone device driver
 User::LeaveIfError(server.UnloadPhoneModule(KTsyName));

 //Close the connection to the tel server and remove it from the cleanup stack
 CleanupStack::PopAndDestroy(&server);
 }   //