NewLC - polymorphic dll - Comments

Re: polymorphic dll

Isha — Mon, 03 Mar 2008 07:04:34 +0100

Thanks Numpty Alert & alh .....
I was very much confused here.But now your replies has made me clear to some extent ......... Also I am trying to know about this topic in detail . But I am not getting the sufficient matter on same except one .pdf from Forum Nokia and SDK help which is not much sufficient. It'll be a great help for me if you'll provide me some link except those.

Regards,
Isha

Re: polymorphic dll

Numpty Alert — Fri, 29 Feb 2008 18:28:01 +0100

P.S.

The term polymorphic DLL is used a concept as well as an implementation which can be confusing. The concept is that of a plugin, previously they were implemented as a DLL which you loaded yourself using RLibrary and the concept and implementation had the same name.
Now they are implemented and loaded using ECom, but conceptually ECom plugins are still polymorphic dlls.

Re: polymorphic dll

Isha — Fri, 29 Feb 2008 06:10:48 +0100

Thanks for the reply. I'll try more to know more in details.

Regards,
Isha

Re: polymorphic dll

Numpty Alert — Thu, 28 Feb 2008 17:27:05 +0100

Polymorphic DLLs was the old way of implementing things, ECom is the new way.

Now that Ecom exists there's no reason to use polymorphic dlls anymore.

Re: polymorphic dll

alh — Thu, 28 Feb 2008 13:17:20 +0100

An exe contains code and data and will be loaded into a process and the entry point will be called as the entry of the main thread in that process.

Dlls also contain code and data, but is meant to be dynamically loaded into processes, either at startup or during runtime.

ECOM is a framework built _on_top_ of normal polymorphic dlls, and add a service to handle control of versions and APIs of polymorphic DLLs, and makes loading of them easier.
ECOM plugins are registered with the ECOM server.

You never strictly must use ECOM, but it is a ready made plugin system for you to use, just the polymorhic DLL concept in itself doesn't help you with version and API control.

Re: polymorphic dll

Isha — Thu, 28 Feb 2008 12:40:55 +0100

Hi ,

I have also one query related to Polymorphic DLL thats why I am asking here itself rather than start new thread.

My question is what is the main difference between Exe , Polymorphic DLL and ECOM as all have one single entry point .Both Polymorphic DLL and ECOM provides abstract API by using virtual mechanism . I am very much confused and not able to distinguish all these .

thanks in advance.

Regards,
Isha

Re: polymorphic dll

alh — Thu, 28 Feb 2008 11:00:11 +0100

You have to explain a bit better what you are asking...

What do you mean by "single interface"? that it has just one function exported?
And what to you mean with "Lookup"? you mean the RLibrary function?

You don't need to use RLibrary if you don't have to unload/reload dll:s, then you can let the kernel load those for you when you start the process (by the normal LIBRARY in mmp fil) and "Lookup" is just the name of the function to access the functions of a DLL by ordinal, ofcourse you will have to use this one if you use RLibrary...

polymorphic dll

thota — Thu, 28 Feb 2008 06:29:41 +0100

hai
this is praveen from cranes software ,bangalore
iam new to symbian c++
my question is

if a polymorphic dll has a single interface why we
required a lookup for polymorphic dll?