Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread manish sharma 
i think it should work using pluginloader something like below:

QObject* getPrmt(QString path)
{
QDir pluginsDir(path)
QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
return loader.instance();
}

and call getPrmt function with any of A/Prmt.dll, B/Prmt.dll?



On Wed, Apr 9, 2014 at 10:34 AM, Vincent Cai w...@cypress.com wrote:

  Dear All,



 I have an Qt application, which uses 2 dll, one is Prmt.dll and the other
 is Core.dll. Core.dll is dependent on Prmt.dll. Prmt.dll has multiple
 instances in different folders, for example: A/Prmt.dll, B/Prmt.dll... The
 Qt application provides an option to choose Prmt.dll, so it need to
 override Prmt.dll in runtime. Is it possible to override dll in runtime in
 Qt?



 Regards,

 Vincent.
  This message and any attachments may contain Cypress (or its
 subsidiaries) confidential information. If it has been received in error,
 please advise the sender and immediately delete this message.

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Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread Koehne Kai 


 -Original Message-
 From: interest-bounces+kai.koehne=digia@qt-project.org
 [mailto:interest-bounces+kai.koehne=digia@qt-project.org] On Behalf Of
 Vincent Cai
 Sent: Wednesday, April 09, 2014 7:04 AM
 To: interest@qt-project.org
 Subject: [Interest] Is it possible to override dll in runtime in Qt?
 
 Dear All,
 
 
 
 I have an Qt application, which uses 2 dll, one is Prmt.dll and the other is
 Core.dll. Core.dll is dependent on Prmt.dll. Prmt.dll has multiple instances 
 in
 different folders, for example: A/Prmt.dll, B/Prmt.dll... The Qt application
 provides an option to choose Prmt.dll, so it need to override Prmt.dll in
 runtime. Is it possible to override dll in runtime in Qt?

Which exact dll is loaded isn't something Qt can really influence. Check out

http://msdn.microsoft.com/en-us/library/windows/desktop/ms682586%28v=vs.85%29.aspx

for the full details on Windows :)

If you're loading Prmt.dll as a hard dependency of Core.dll there's nothing you 
can do in the programming logic itself, and you've to set up things from the 
outside (e.g. by changing a PATH environment variable in a launch.bat file , 
or something similar). If you're loading Prmt.dll dynamically at runtime (like 
a plugin), you can set an absolute path in your code.

Regards

Kai
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Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread Vincent Cai 
Hi manish,

   Thanks for the reply.
   I am totally new to QPlugin and QLibrary.
   I don't quite understand your meaning.
   With your method below, can I load A/Prmt.dll then unload 
A/Prmt.dll and then load B/Prmt.dll in runtime without restarting Application?
   BTW, Core.dll is dependent on Prmt.dll, how can Core.dll know 
access symbols in Prmt.dll after changing Prmt.dll?

Regards,
Vincent.
From: manish sharma [mailto:83.man...@gmail.com]
Sent: Wednesday, April 09, 2014 2:42 PM
To: Vincent Cai
Cc: interest@qt-project.org
Subject: Re: [Interest] Is it possible to override dll in runtime in Qt?

i think it should work using pluginloader something like below:

QObject* getPrmt(QString path)
{
QDir pluginsDir(path)
QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
return loader.instance();
}
and call getPrmt function with any of A/Prmt.dll, B/Prmt.dll?

On Wed, Apr 9, 2014 at 10:34 AM, Vincent Cai 
w...@cypress.commailto:w...@cypress.com wrote:
Dear All,

I have an Qt application, which uses 2 dll, one is Prmt.dll and the other is 
Core.dll. Core.dll is dependent on Prmt.dll. Prmt.dll has multiple instances in 
different folders, for example: A/Prmt.dll, B/Prmt.dll... The Qt application 
provides an option to choose Prmt.dll, so it need to override Prmt.dll in 
runtime. Is it possible to override dll in runtime in Qt?

Regards,
Vincent.
This message and any attachments may contain Cypress (or its subsidiaries) 
confidential information. If it has been received in error, please advise the 
sender and immediately delete this message.

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Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread manish sharma 
I think you might have to design your application something like below:

For instance all the Prmt.dlls should implement a common interface for
instance: PrmtInterface and place it under PrmtInterface.h

And your Core.dll only know about PrmtInterface.h, it should not link to
any of the Prmt.dll. And then you go on implementing Prmt.dlls and place it
to different folders. And at run time you should use QPluginLoader to
load/unload appropriate plugin.


Hope this help!


On Wed, Apr 9, 2014 at 12:22 PM, Vincent Cai w...@cypress.com wrote:

  Hi manish,



Thanks for the reply.

I am totally new to QPlugin and QLibrary.

I don't quite understand your meaning.

With your method below, can I load A/Prmt.dll then unload
 A/Prmt.dll and then load B/Prmt.dll in runtime without restarting
 Application?

BTW, Core.dll is dependent on Prmt.dll, how can Core.dll
 know access symbols in Prmt.dll after changing Prmt.dll?



 Regards,

 Vincent.

 *From:* manish sharma [mailto:83.man...@gmail.com]
 *Sent:* Wednesday, April 09, 2014 2:42 PM
 *To:* Vincent Cai
 *Cc:* interest@qt-project.org
 *Subject:* Re: [Interest] Is it possible to override dll in runtime in Qt?



 i think it should work using pluginloader something like below:

 QObject* getPrmt(QString path)
 {

 QDir pluginsDir(path)

 QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
 return loader.instance();
 }

 and call getPrmt function with any of A/Prmt.dll, B/Prmt.dll?



 On Wed, Apr 9, 2014 at 10:34 AM, Vincent Cai w...@cypress.com wrote:

 Dear All,



 I have an Qt application, which uses 2 dll, one is Prmt.dll and the other
 is Core.dll. Core.dll is dependent on Prmt.dll. Prmt.dll has multiple
 instances in different folders, for example: A/Prmt.dll, B/Prmt.dll... The
 Qt application provides an option to choose Prmt.dll, so it need to
 override Prmt.dll in runtime. Is it possible to override dll in runtime in
 Qt?



 Regards,

 Vincent.

 This message and any attachments may contain Cypress (or its subsidiaries)
 confidential information. If it has been received in error, please advise
 the sender and immediately delete this message.


 ___
 Interest mailing list
 Interest@qt-project.org
 http://lists.qt-project.org/mailman/listinfo/interest


  This message and any attachments may contain Cypress (or its
 subsidiaries) confidential information. If it has been received in error,
 please advise the sender and immediately delete this message.

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Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread manish sharma 
you might want to take a look at
http://qt-project.org/doc/qt-5/qtwidgets-tools-plugandpaint-example.html



On Wed, Apr 9, 2014 at 3:29 PM, manish sharma 83.man...@gmail.com wrote:

 I think you might have to design your application something like below:

 For instance all the Prmt.dlls should implement a common interface for
 instance: PrmtInterface and place it under PrmtInterface.h

 And your Core.dll only know about PrmtInterface.h, it should not link to
 any of the Prmt.dll. And then you go on implementing Prmt.dlls and place it
 to different folders. And at run time you should use QPluginLoader to
 load/unload appropriate plugin.


 Hope this help!


 On Wed, Apr 9, 2014 at 12:22 PM, Vincent Cai w...@cypress.com wrote:

  Hi manish,



Thanks for the reply.

I am totally new to QPlugin and QLibrary.

I don't quite understand your meaning.

With your method below, can I load A/Prmt.dll then unload
 A/Prmt.dll and then load B/Prmt.dll in runtime without restarting
 Application?

BTW, Core.dll is dependent on Prmt.dll, how can Core.dll
 know access symbols in Prmt.dll after changing Prmt.dll?



 Regards,

 Vincent.

 *From:* manish sharma [mailto:83.man...@gmail.com]
 *Sent:* Wednesday, April 09, 2014 2:42 PM
 *To:* Vincent Cai
 *Cc:* interest@qt-project.org
 *Subject:* Re: [Interest] Is it possible to override dll in runtime in
 Qt?



 i think it should work using pluginloader something like below:

 QObject* getPrmt(QString path)
 {

 QDir pluginsDir(path)

 QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
 return loader.instance();
 }

 and call getPrmt function with any of A/Prmt.dll, B/Prmt.dll?



 On Wed, Apr 9, 2014 at 10:34 AM, Vincent Cai w...@cypress.com wrote:

 Dear All,



 I have an Qt application, which uses 2 dll, one is Prmt.dll and the other
 is Core.dll. Core.dll is dependent on Prmt.dll. Prmt.dll has multiple
 instances in different folders, for example: A/Prmt.dll, B/Prmt.dll... The
 Qt application provides an option to choose Prmt.dll, so it need to
 override Prmt.dll in runtime. Is it possible to override dll in runtime in
 Qt?



 Regards,

 Vincent.

 This message and any attachments may contain Cypress (or its
 subsidiaries) confidential information. If it has been received in error,
 please advise the sender and immediately delete this message.


 ___
 Interest mailing list
 Interest@qt-project.org
 http://lists.qt-project.org/mailman/listinfo/interest


  This message and any attachments may contain Cypress (or its
 subsidiaries) confidential information. If it has been received in error,
 please advise the sender and immediately delete this message.



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Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread Vincent Cai 
Thanks a lot!
I have already implemented Core.dll and Prmt.dll in the way you suggested.
Will learn how to use QPluginLoder for such case.
If anyone can provide a sample code, that would be greatly helpful. :)

From: manish sharma [mailto:83.man...@gmail.com]
Sent: Wednesday, April 09, 2014 6:06 PM
To: Vincent Cai
Cc: interest@qt-project.org
Subject: Re: [Interest] Is it possible to override dll in runtime in Qt?

you might want to take a look at 
http://qt-project.org/doc/qt-5/qtwidgets-tools-plugandpaint-example.html

On Wed, Apr 9, 2014 at 3:29 PM, manish sharma 
83.man...@gmail.commailto:83.man...@gmail.com wrote:
I think you might have to design your application something like below:
For instance all the Prmt.dlls should implement a common interface for 
instance: PrmtInterface and place it under PrmtInterface.h
And your Core.dll only know about PrmtInterface.h, it should not link to any of 
the Prmt.dll. And then you go on implementing Prmt.dlls and place it to 
different folders. And at run time you should use QPluginLoader to load/unload 
appropriate plugin.

Hope this help!

On Wed, Apr 9, 2014 at 12:22 PM, Vincent Cai 
w...@cypress.commailto:w...@cypress.com wrote:
Hi manish,

   Thanks for the reply.
   I am totally new to QPlugin and QLibrary.
   I don't quite understand your meaning.
   With your method below, can I load A/Prmt.dll then unload 
A/Prmt.dll and then load B/Prmt.dll in runtime without restarting Application?
   BTW, Core.dll is dependent on Prmt.dll, how can Core.dll know 
access symbols in Prmt.dll after changing Prmt.dll?

Regards,
Vincent.
From: manish sharma [mailto:83.man...@gmail.commailto:83.man...@gmail.com]
Sent: Wednesday, April 09, 2014 2:42 PM
To: Vincent Cai
Cc: interest@qt-project.orgmailto:interest@qt-project.org
Subject: Re: [Interest] Is it possible to override dll in runtime in Qt?

i think it should work using pluginloader something like below:

QObject* getPrmt(QString path)
{
QDir pluginsDir(path)
QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
return loader.instance();
}
and call getPrmt function with any of A/Prmt.dll, B/Prmt.dll?

On Wed, Apr 9, 2014 at 10:34 AM, Vincent Cai 
w...@cypress.commailto:w...@cypress.com wrote:
Dear All,

I have an Qt application, which uses 2 dll, one is Prmt.dll and the other is 
Core.dll. Core.dll is dependent on Prmt.dll. Prmt.dll has multiple instances in 
different folders, for example: A/Prmt.dll, B/Prmt.dll... The Qt application 
provides an option to choose Prmt.dll, so it need to override Prmt.dll in 
runtime. Is it possible to override dll in runtime in Qt?

Regards,
Vincent.
This message and any attachments may contain Cypress (or its subsidiaries) 
confidential information. If it has been received in error, please advise the 
sender and immediately delete this message.

___
Interest mailing list
Interest@qt-project.orgmailto:Interest@qt-project.org
http://lists.qt-project.org/mailman/listinfo/interest

This message and any attachments may contain Cypress (or its subsidiaries) 
confidential information. If it has been received in error, please advise the 
sender and immediately delete this message.


This message and any attachments may contain Cypress (or its subsidiaries) 
confidential information. If it has been received in error, please advise the 
sender and immediately delete this message.
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Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread Thiago Macieira 
Em qua 09 abr 2014, às 05:04:27, Vincent Cai escreveu:
 Dear All,
 
 I have an Qt application, which uses 2 dll, one is Prmt.dll and the other is
 Core.dll. Core.dll is dependent on Prmt.dll. Prmt.dll has multiple
 instances in different folders, for example: A/Prmt.dll, B/Prmt.dll... The
 Qt application provides an option to choose Prmt.dll, so it need to
 override Prmt.dll in runtime. Is it possible to override dll in runtime in
 Qt?

LoadLibrary the DLL that you want before you load any DLLs that depend on it.

And cross your fingers. We're talking about Windows.
-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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Re: [Interest] Is it possible to override dll in runtime in Qt?

2014-04-09 Thread Thiago Macieira 
Em qua 09 abr 2014, às 06:52:01, Vincent Cai escreveu:
With your method below, can I load A/Prmt.dll then unload
 A/Prmt.dll and then load B/Prmt.dll in runtime without restarting
 Application?

Not a good idea. Unloading plugins is not recommended. Simply restart the 
application if you need to change plugins.

Also, QPluginLoader needs to load something that is a Qt plugin. A generic DLL 
does not qualify. You'd need to use QLibrary directly or, better yet, Win32 
LoadLibrary.

 BTW, Core.dll is dependent on Prmt.dll, how can Core.dll know
 access symbols in Prmt.dll after changing Prmt.dll?

You have to unload Core.dll too. Hence, please use LoadLibrary for both DLLs 
and unload them both when you're done.

And cross your fingers.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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