All about DLL's...

[A_Surender]

Dear Gurus,

what is an extension DLL. what is the significant difference between a "regular DLL" and "extension DLL".?

[ahoodin]

Extension DLLs implements reusable classes from MFC classes. They can export entire classes. Client applications can create objects of that class and call its functions.

So it is an MFC Thing. The classes can not be used by Windows 32 apps. If you want that you will need to build a regular dll.

Oh yes, I must define what an export is: A way to make a function, object / variable usable from one library or application to another application.

Here is a link that explains how to build and use one:
http://www.dotnetheaven.com/Uploadfile/mahesh/DLLBasicsPart105192005020909AM/DLLBasicsPart1.aspx?ArticleID=0761024a-f5f8-43f1-9e7a-e1da67a862e1

HTH,

[A_Surender]

What i understand from your message is :

Extension DLL's and regular DLL's are differt. So their creation and implementation.

Does the extension DLL shares the implementation of Abstrat class concept. what i mean is,..... their is an Abstract class whose functionality will be implemented by another class.

Does extension DLL implement the functionality of yet another (Abstract class) DLL?


Thank you.
-Suren

[ahoodin]

In order to export a class, to the APP, the program that you are exporting to usually will have to have a copy of the class header.

Otherwise how could u use the class in the app?

Using the abstract class concept in MFC is a technical difficulty in its own right in many cases. It does not operate the way C++ was designed. Consider the point that when you create a dialog class, just try to use your dialog as a base class and just try to extend the functionality of your new class that inherits from the base. This is no easy task.

HTH

[Bornish]

Extension DLLs are regular DLLs, but regular DLLs are not "usually" extension DLLs. :D
As ahoodin said, "it is an MFC Thing".
I gave some useful links about extension DLLs in some other thread:
http://www.codeguru.com/forum/showpost.php?p=1361415&postcount=11.
Regards,

[A_Surender]

Thank you Guru(s);


Now i have understood that a regular DLL is nothing but a "C kind" of exporting functions but implemented through MFC way.

And Extension dll are nothing but "C++ kind" of exporting a function through encapsulation of a class, and thus using it by creating an object of the class.



Thank you,
Suren.