what 's mean of Extension_() in CSession Class

[yinquan]

I saw Extension_() function during studing usage of CSession.
Does my own class inherit this function from CSession? what usage of Extension_()?

In symbian API, I saw a lot of Extension_() function in many vary class. How does Those functions implement extension function.

[david.caabeiro]

What use would you make out of it? They're mostly meant for internal use probably.

[laa-laa]

These "extension" functions are really just empty placeholders for the future. They enable adding new functions to base classes without breaking binary compatibility of derived classes.

Lauri

[yinquan]

What use would you make out of it? They're mostly meant for internal use probably.

According your explain, function like Extension_() is used internal Symbian API, and Common Devoloper don't need to use this function.

But I don't know whether I can use this function to extension my application.

[david.caabeiro]

Actually Lauri's answer is more precise. Anyway, these functions are not meant to be used by application developers.

[yinquan]

Thanks. I know. This API will be called reference API of Symbian.
Thanks a lot again.

[pirosl]

I saw Extension_() function during studing usage of CSession.
Does my own class inherit this function from CSession? what usage of Extension_()?

In symbian API, I saw a lot of Extension_() function in many vary class. How does Those functions implement extension function.

It's just a standard way to make a class future proof. E.g. if Symbian wants to extends smth in the future will probably use those extend methods since they promised binary and source compatibility between versions.
And....you can't use them

[hotcheese]

But I don't know whether I can use this function to extension my application.

THe implementation of this function will be to do nothing - so how can you use something which does nothing to extend your application?