How to do inheritance in ATL

Question

0.00/5 (No votes)

See more:

Hello Friends,

I have to expose "ATL simple object" interface.

Now, I wanted to expose 3 interface objects. Each one has some common functionality, hence I am trying to keep common functionality in abstract class.

Now, my requirement is that each three class should have their own methods plus common functionilty [methods like Lock] inherited from common abstract base class.

Please suggest. Helpfull link would really help.

Posted 21-May-12 0:03am

Rahul.RK

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Pablo Aliskevicius · Answer 1 · 2012-05-21T00:23:00

You have to define an interface in your IDL file, and implement it in all the ATL objects that 'inherit' it.

About IDL, start here:
http://www.google.co.il/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CFcQFjAA&url=http%3A%2F%2Fmsdn.microsoft.com%2Fen-us%2Flibrary%2Fwindows%2Fdesktop%2Fms690150(v%3Dvs.85).aspx&ei=fha6T_PeJNOg8gOPpeHJCg&usg=AFQjCNGyHC6ucN5yX0TXpX7PmNammxutig&sig2=Sufx_8vwOSaxqsftzdMtDA[^]

About implementing interfaces:

http://msdn.microsoft.com/en-us/library/35tb9xw9(v=vs.80).aspx[^]

http://stackoverflow.com/questions/2190993/creating-an-atl-com-object-that-implements-a-specific-interface[^]

Hope this helps,
Pablo.

Aescleal · Answer 2 · 2012-05-21T00:31:00

In addition to the references Pablo's given you have a look at "Essential COM" by Don Box. It's a bit dated but still the definitive tutorial on COM programming.

Another thing to watch out for... Implementation inheritance is the tightest form of coupling you can get between two classes. By giving classes a common base with any form of implementation you're coupling the base to all the derived classes AND each derived class to every other derived class. If you want to change an implementation of one of the derived classes then you might have to change the base class which means an implicit change to all the other derived classes.

If you want common functionality consider using free functions and/or a contained object to get the effect you want. It'll make your design less fragile.

PS: Just thought, ATL uses the Curiously Recursive Template pattern first documented by Jim Coplien in "The C++ Report" yonks ago. It's a key feature of ATL's architecture so it might be worth looking it up. In case you're wondering it's a way of call derived class functions from a base class without using virtual functions.

How to do inheritance in ATL

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0