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Archived:Changing asynchronous method to synchronous in Symbian C++

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__NOTOC__
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[[Category:Symbian C++]][[Category:Code Snippet]][[Category:S60 3rd Edition (initial release)]][[Category:Code Snippet]]
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{{Archived|timestamp=20120313125306|user=roy.debjit| }}
 
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{|style="background:#eceff2" width="660px" border="1" cellpadding="5" cellspacing="0"
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|-
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|'''ID''' ||
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|'''Creation date''' || May 21, 2008
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|-
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|'''Platform''' || S60 3rd Edition, MR
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|'''Tested on devices''' || Nokia N95
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|-
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|'''Category''' || Symbian C++
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|'''Subcategory''' || Code Examples
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|-
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|}
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{|style="background:#eceff2" width="660px" border="1" cellpadding="5" cellspacing="0"
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|-
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|'''Keywords (APIs, classes, methods, functions):''' CActiveSchedulerWait, CActive, TRequestStatus
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|}
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 +
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 +
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|devices= Nokia N95
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|sdk= <!-- SDK(s) built and tested against (e.g. [http://linktosdkdownload/ Nokia Qt SDK 1.1]) -->
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|platform= S60 3rd Edition, MR
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|capabilities= <!-- Capabilities required by the article/code example (e.g. Location, NetworkServices. -->
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|subcategory= Code Examples
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==Overview==
 
==Overview==
This code snippet shows how to change some asynchronous method interface into
+
{{Abstract|This code snippet shows how to change an asynchronous method interface to a synchronous method. This can be done with CActiveSchedulerWait.}}
synchronous. This can be done with CActiveSchedulerWait.
+
  
There is two different synchronous methods:
+
There are two different synchronous methods:
* CMyClass::DoAsynchronousL() uses CActiveSchedulerWait for waiting asynchronous method that completes into CMyClass::AsyncComplete()
+
* CMyClass::DoAsynchronousL() uses CActiveSchedulerWait for waiting for the asynchronous method that completes with CMyClass::AsyncComplete()
* CMyClass::DoAsynchronousWithStatusL() uses CActiveSchedulerWait for waiting asynchronous method that has TRequestStatus in its interface. Method completes into CMyClass::RunL().
+
* CMyClass::DoAsynchronousWithStatusL() uses CActiveSchedulerWait for waiting for the asynchronous method that has TRequestStatus in its interface. The method completes with CMyClass::RunL().
  
See more about using CActiveSchedulerWait from [[Using_CActiveSchedulerWait]]
+
For more information on using CActiveSchedulerWait, see article  [[Archived:Using CActiveSchedulerWait]]
  
 
==MMP file==
 
==MMP file==
 
The following capabilities and libraries are required:
 
The following capabilities and libraries are required:
 
<code cpp>
 
<code cpp>
CAPABILITY   None
+
CAPABILITY None
LIBRARY       euser.lib
+
LIBRARY euser.lib
 
</code>
 
</code>
  
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     };         
 
     };         
  
class CMyClass : public CActive
+
class CMyClass : public CActive, MAsynchIF
 
     {
 
     {
 
     public:
 
     public:
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         TInt DoAsynchronousWithStatusL();
 
         TInt DoAsynchronousWithStatusL();
  
     pritave: // From MAsynchIF (CSomeAsyncClass)
+
     private: // From MAsynchIF (CSomeAsyncClass)
 
         void AsyncComplete(TInt aResult);
 
         void AsyncComplete(TInt aResult);
 
      
 
      
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     private:
 
     private:
 
         CSomeAsyncClass*      iSomeAsyncClass;
 
         CSomeAsyncClass*      iSomeAsyncClass;
         CActiveSchedulerWait   iSchedulerWait;
+
         CActiveSchedulerWait iSchedulerWait;
         TInt                   iResult;
+
         TInt iResult;
 
     };
 
     };
 
</code>
 
</code>
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     }   
 
     }   
  
// This is synchronous method even it call some asynchronous interface that
+
// This is a synchronous method even though it calls an asynchronous interface that
// completes into CMyClass::AsyncComplete()
+
// completes with CMyClass::AsyncComplete()
 
TInt CMyClass::DoAsynchronousL()
 
TInt CMyClass::DoAsynchronousL()
 
     {
 
     {
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     }
 
     }
  
// This is synchronous method even it call some asynchronous interface that
+
// This is an synchronous method even though it calls an asynchronous interface that
// completes into CMyClass::RunL() because it uses TRequestStatus as
+
// completes with CMyClass::RunL() because it uses TRequestStatus as
 
// a parameter
 
// a parameter
Int CMyClass::DoAsynchronousWithStatusL()
+
TInt CMyClass::DoAsynchronousWithStatusL()
 
     {
 
     {
 
     if (!IsActive())
 
     if (!IsActive())
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void CMyClass::DoCancel()
 
void CMyClass::DoCancel()
 
     {
 
     {
     // This cancels DoAsynchronousWithStatusL() method
+
     // This cancels the DoAsynchronousWithStatusL() method
 
     iResult = KErrCancel;
 
     iResult = KErrCancel;
 
     iSchedulerWait.AsyncStop();
 
     iSchedulerWait.AsyncStop();
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==Postconditions==
 
==Postconditions==
Asynchronous methods look a like synchronous.
+
The asynchronous methods looks like a synchronous method.
  
 
==See also==
 
==See also==
[[Using_CActiveSchedulerWait]]
+
[[Archived:Using CActiveSchedulerWait]]
 
+
[[Category:Symbian C++]][[Category:Code Examples]]
+

Latest revision as of 01:26, 25 August 2012

Archived.pngArchived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.

Article Metadata
Tested with
Devices(s): Nokia N95
Compatibility
Platform(s): S60 3rd Edition, MR
S60 3rd Edition (initial release)
Article
Keywords: CActiveSchedulerWait, CActive, TRequestStatus
Created: tepaa (21 May 2008)
Last edited: lpvalente (25 Aug 2012)

Contents

[edit] Overview

This code snippet shows how to change an asynchronous method interface to a synchronous method. This can be done with CActiveSchedulerWait.

There are two different synchronous methods:

  • CMyClass::DoAsynchronousL() uses CActiveSchedulerWait for waiting for the asynchronous method that completes with CMyClass::AsyncComplete()
  • CMyClass::DoAsynchronousWithStatusL() uses CActiveSchedulerWait for waiting for the asynchronous method that has TRequestStatus in its interface. The method completes with CMyClass::RunL().

For more information on using CActiveSchedulerWait, see article Archived:Using CActiveSchedulerWait

[edit] MMP file

The following capabilities and libraries are required:

CAPABILITY None
LIBRARY euser.lib

[edit] Header

#include <e32base.h>
 
// for CSomeAsyncClass
class MAsynchIF
{
public:
void AsyncComplete(TInt aResult);
};
 
class CMyClass : public CActive, MAsynchIF
{
public:
static CMyClass* NewLC();
virtual ~CMyClass();
 
// Synchronous methods
TInt DoAsynchronousL();
TInt DoAsynchronousWithStatusL();
 
private: // From MAsynchIF (CSomeAsyncClass)
void AsyncComplete(TInt aResult);
 
private: // From CActive
void RunL();
void DoCancel();
 
private:
CSomeAsyncClass* iSomeAsyncClass;
CActiveSchedulerWait iSchedulerWait;
TInt iResult;
};

[edit] Source

CMyClass* CMyClass::NewLC()
{
CMyClass* self = new (ELeave) CMyClass();
CleanupStack::PushL(self);
self->ConstructL();
return self;
}
 
CMyClass::CMyClass()
: CActive(CActive::EPriorityStandard)
{
}
 
void CMyClass::ConstructL()
{
CActiveScheduler::Add(this);
iSomeAsyncClass = CSomeAsyncClass::NewL(this);
}
 
CMyClass::~CMyClass()
{
Cancel();
delete iSomeAsyncClass;
}
 
// This is a synchronous method even though it calls an asynchronous interface that
// completes with CMyClass::AsyncComplete()
TInt CMyClass::DoAsynchronousL()
{
User::LeaveIfError(iSomeAsyncClass->SomeAsynchronousIfL());
 
iSchedulerWait.Start();
// Continues here after CMyClass::AsyncComplete() is called
// by CSomeAsyncClass.
 
return iResult;
}
 
void CMyClass::AsyncComplete(TInt aResult)
{
iResult = aResult;
iSchedulerWait.AsyncStop();
}
 
// This is an synchronous method even though it calls an asynchronous interface that
// completes with CMyClass::RunL() because it uses TRequestStatus as
// a parameter
TInt CMyClass::DoAsynchronousWithStatusL()
{
if (!IsActive())
{
User::LeaveIfError(iSomeAsyncClass->SomeAsynchronousIfL(iStatus));
SetActive();
 
iSchedulerWait.Start();
// Continues here after CMyClass::RunL() is called
// by CSomeAsyncClass.
}
else
{
User::Leave(KErrNotReady);
}
return iResult;
}
 
void CMyClass::RunL()
{
// This is called when DoAsynchronousWithStatusL() completes
iResult = iStatus.Int();
iSchedulerWait.AsyncStop();
}
 
void CMyClass::DoCancel()
{
// This cancels the DoAsynchronousWithStatusL() method
iResult = KErrCancel;
iSchedulerWait.AsyncStop();
}

[edit] Postconditions

The asynchronous methods looks like a synchronous method.

[edit] See also

Archived:Using CActiveSchedulerWait

This page was last modified on 25 August 2012, at 01:26.
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